Things is, people are kinda tired of the "exagerated/acting" vibes that anime/jp industry got.
And that is why Kazuma of Konosuba (anticliche)(like Deadpool) is liked.
Because there is this smoothless and
natural vibes to it.
Also not sure if you know, but humans, when act, voluntarily or involuntarily, "fake" it. Some more obvious than others. (goal of acting being to reduce that)
----------------
What you should do, isnt to think "this character will say that or this bc plot need it"
but more like "what will this character say in this situation OR what would I(the author) say if i was in his-her shoes"
Kinda like the seiyuu of kazuma ad-libed : yes yes kazuma-desu (the joke when others call kazuma ! kazuma!)(it wasnt in script at all but purely inserted by the voice actor)
So or you insert yourself in the character to think what they would say so it feels natural
or you ask your friend to do it for you.
Basically its like the self-insert method of acting. But likewise, be cautious of not being able to "get out".
-------------------------
Example :
What people want or crave, is the NORMAL BRAIN person like in this video:
NOT the retarded characters just here for the "plot".
Basically natural = normality.