Hello, friend!
Let's start off with what you do well. Your descriptions and word choices are very good. From that aspect, the story is very good and easy to read. Where I feel you need to work on isn't your prose so much as learning the rules of elements and style. If you'll allow it, I'm going to put a majority of the text here and go through it (please keep in mind that I am not a master and I do rely on Grammarly and an editor to help me fix my own issues)
Paragraph 1:
The ships traveled west from Vinderfell filled to the brim with refuges from the Southern Kingdoms, and as the ship traveled across the Rox sea thunder gathered ahead. The ocean danced back and forth with a fury that reminded them that Tresvaha was not to be messed with, so many refuges paid their respects to the Sea Goddess by throwing half their food into the water and sending a silent prayer. One man was a little rustled and as he spat in the sea the skies clapped. “Dammit! What are we supposed to do now? Restart? I’ve invested years and money into my business and now what am I supposed to do? Start over? Pah!” The man next to him shook his head then lit his rolled paper filled with tobacco.
“None of us want to restart Lenny, but we have no choice. The Blight is at an all time high. The Southern Kingdoms has called for reinforcements, but they say that we’re so overnumbered with the Blight we can no longer stay until it’s eradicated.” The man, Lenny, shook his head.
Shorter paragraphs are easier to follow, but you also don't want too short of paragraphs otherwise the piece comes off very staccato-y. Like sentences, paragraphs should have a subject. If the main actor of the sentence is different from the main actor of the paragraph it should either be rewritten for consistency within the paragraph or be made its own paragraph.
With that in mind, the first paragraph would change as follows:
The ships traveled west from Vinderfell filled to the brim with refuges from the Southern Kingdoms, and as the ship traveled across the Rox sea thunder gathered ahead. The ocean danced back and forth with a fury that reminded them that Tresvaha was not to be messed with, so many refuges paid their respects to the Sea Goddess by throwing half their food into the water and sending a silent prayer.
One man was a little rustled and as he spat in the sea the skies clapped. “Dammit! What are we supposed to do now? Restart? I’ve invested years and money into my business and now what am I supposed to do? Start over? Pah!” The man next to him shook his head then lit his rolled paper filled with tobacco.
“None of us want to restart Lenny, but we have no choice. The Blight is at an all time high. The Southern Kingdoms has called for reinforcements, but they say that we’re so overnumbered with the Blight we can no longer stay until it’s eradicated.” The man, Lenny, shook his head.
Now we've split it into two main actors "the voyage" and "one man." The thoughts are more organized and easier for the reader to comprehend.
Once again, I'd like to focus on our new first paragraph. Longer sentences do not mean better sentences. At the end of the day, we want to focus on clarity. Conjoin sentences where the subject is the same; separate where different.
The ships traveled west from Vinderfell filled to the brim with refuges from the Southern Kingdoms, and as the ship traveled across the Rox sea thunder gathered ahead.
This is grammatically correct in its connection, but the subjects are deceptively different. Part 1, the subject is the ships. Part 2, the ships are in an independent clause (which is missing its comma) and the subject is the thunder (technicality here. Thunder is a sound and cannot gather.
Thunderclouds, however, do). The sentences will flow better and will be easier to understand if we remove the conjunction (One last thing to note, "sea" should be capitalized as it's part of the name. It's the Pacific Ocean, not the Pacific ocean). Also, as the refugees and ships are one in this, we can replace the second "ships" with "they."
The ships traveled west from Vinderfell filled to the brim with refuges from the Southern Kingdoms. As they traveled across the Rox Sea, thunderclouds gathered ahead.
The following sentence also has different subjects in its independent parts. So, once again, we should separate them out. Also, you have a nebulous "them" in there. Who are they? You've made reference to refugees once, but they've never been the subject of the sentence, nor are they part of the sentence in which "them" appears. Taking those into account, we can remake the second sentence as follows:
The ocean danced back and forth with a fury that reminded all on board that Tresvaha was not to be messed with. Many refuges paid their respects to the Sea Goddess by throwing half their food into the water and sending a silent prayer.
I would like to pause for a bit and say that I really like the imagery you create with that section. Also, I would like to point out that we've ended the sentence with a preposition, but modern English (specifically American) is really leaving that rule behind in many instances. We could change it to "Trevasha was not one with whom to be messed" but I left it in your original structure.
Putting it all together we get:
The ships traveled west from Vinderfell filled to the brim with refuges from the Southern Kingdoms. As they traveled across the Rox Sea, thunderclouds gathered ahead. The ocean danced back and forth with a fury that reminded all on board that Tresvaha was not to be messed with. Many refuges paid their respects to the Sea Goddess by throwing half their food into the water and sending a silent prayer.
One man was a little rustled and as he spat in the sea the skies clapped. “Dammit! What are we supposed to do now? Restart? I’ve invested years and money into my business and now what am I supposed to do? Start over? Pah!” The man next to him shook his head then lit his rolled paper filled with tobacco.
“None of us want to restart Lenny, but we have no choice. The Blight is at an all time high. The Southern Kingdoms has called for reinforcements, but they say that we’re so overnumbered with the Blight we can no longer stay until it’s eradicated.” The man, Lenny, shook his head.
The next part we'll look at really address what you've said you want to focus on, dynamic characters and believable dialogue.
One man was a little rustled and as he spat in the sea the skies clapped. “Dammit! What are we supposed to do now? Restart? I’ve invested years and money into my business and now what am I supposed to do? Start over? Pah!” The man next to him shook his head then lit his rolled paper filled with tobacco.
“None of us want to restart Lenny, but we have no choice. The Blight is at an all time high. The Southern Kingdoms has called for reinforcements, but they say that we’re so overnumbered with the Blight we can no longer stay until it’s eradicated.” The man, Lenny, shook his head.
"One man" is the antithesis of dynamic. It tells us nothing. It gives us no visuals to the point that it becomes detracting. He's not a blank slate because the slate hasn't even been made yet. Who is this man? Is he a member of the crew? A refugee? The expedition's leader? The ship's captain? Going from later context, it seems like he's one of the former two, but it's still not clear as to which one.
My second point of contention with this section is the order of operations. In the first paragraph, you have
refugees throwing
half their food into the ocean because of their reverence/fear of the sea goddess. So having this guy spit in the ocean shows that he does not share that reverence or fear, which is totally fine and works wonders for character creation, but it's followed by thunder, which can be taken as a response from the ocean for his lack of reverence (which based on the reactions of others does not seem to be the case).
The dialogue here is fine and works very well with the setup. He's talking to himself. No "said" is required. However, the actor of the sentence of the dialogue is a different person and should be in its own paragraph to prevent confusion. Each new speaker gets a new paragraph. This also goes for new speakers who don't actually speak.
Last, the reason as to why he is rustled is not clear. Is it because of the violent seas? Because starving refugees are wasting good food over superstitions? Or because the inclement weather means they might have to turn back? In the following rewrite, please note that I am going by what I best inferred from the passage in its entirety.
The skies clapped and the expedition's leader spat into the sea. He couldn't contain his irritation. “Dammit! What are we supposed to do now? Restart? I’ve invested years and money into my business and now what am I supposed to do? Start over? Pah!”
The man next to him shook his head then lit his rolled paper filled with tobacco.
“None of us want to restart Lenny, but we have no choice. The Blight is at an all time high. The Southern Kingdoms has called for reinforcements, but they say that we’re so overnumbered with the Blight we can no longer stay until it’s eradicated.” The man, Lenny, shook his head.
In this, I threw out the "different subject, different sentence" rule to create a feeling of immediacy and cause and effect. He spat in the sea because of the thunder and immediately after the sound.
The next "man" that we have, even from the context of the rest of the passage, I have no idea who he might be. As this "man" is the speaker of the following dialogue, put it in the same paragraph as his actions. Also, for natural dialogue, this might as well be a soliloquy. He's speaking three sentences, two with conjunctions, and repeating information that Lenny already knows (even if the reader doesn't, Lenny does). This just wouldn't fly in normal conversation, let alone with someone who is irritated. You need to slow the rollout of this information and make it more of a back and forth, especially since Lenny thinks it's hogwash. Go talk to an antivaxxer about COVID. You won't make it past "high" before they run over you.
Also, the last sentence, you've already defined who Lenny is. There is no need to redefine him. Also, his action and other guy dialogue means new paragraph. (Oh, when addressing someone in dialogue, their name is separated with comas)
The skies clapped and the expedition's leader spat into the sea. He couldn't contain his irritation. “Dammit! What are we supposed to do now? Restart? I’ve invested years and money into my business and now what am I supposed to do? Start over? Pah!”
His assistant standing next to him shook his head then lit his rolled paper filled with tobacco. “None of us want to restart, Lenny, but we have no choice."
"Sure we do."
"The Blight is at an all time high."
"Blight-schmite"
"Look, The Southern Kingdoms has called for reinforcements, but they say that we’re so overnumbered with the Blight we can no longer stay until it’s eradicated.”
Lenny shook his head.
All together now:
The ships traveled west from Vinderfell filled to the brim with refugees from the Southern Kingdoms. As they traveled across the Rox Sea, thunderclouds gathered ahead. The ocean danced back and forth with a fury that reminded all on board that Tresvaha was not to be messed with. Many refuges paid their respects to the Sea Goddess by throwing half their food into the water and sending a silent prayer.
The skies clapped and the expedition's leader spat into the sea. He couldn't contain his irritation. “Dammit! What are we supposed to do now? Restart? I’ve invested years and money into my business and now what am I supposed to do? Start over? Pah!”
His assistant standing next to him shook his head then lit his rolled paper filled with tobacco. “None of us want to restart, Lenny, but we have no choice."
"Sure we do."
"The Blight is at an all time high."
"Blight-schmite"
"Look, The Southern Kingdoms has called for reinforcements, but they say that we’re so overnumbered with the Blight we can no longer stay until it’s eradicated.”
Lenny shook his head.
