Beastmen are Anthropomorphic with enhanced strengh
Dragonfolk are similar but with longer life spans
Fairies are similar to the ones from Winx Club, but with more insect features
As for personality, she will be similar to Alex, unwanted by her clan, she is sold as a slave to fight in the arena.
So...
Basically a Furry, a Scaly, or a Fairy?
Which one of the three do you enjoy writing most?
Which one do you feel fits the character (Alex) better?
Which do you feel would be the most rewarding narratively speaking?
Does it truly change the narrative, or are they just interchangeable aesthetics?
Or if you are really stuck, and it doesn't change your narrative much, you can always just roll a d6 (six-sided die) and leave it to fate and run with whatever result you get.
If you're thinking arena, in the gladiatorial sense, the Beastfolk or Dragonfolk/Lizardfolk would probably fit better thematically.
As for actual advice though... Here's a little focusing exercise and thought-experiment approach that I use regularly.
Close your eyes and clear your mind.
Take a few deep breaths, and let her come into focus in your mind.
She's standing there in the arena, a few feet away from you. The lighting is set perfectly so you can see her clearly.
What does she look like?
What does she act like?
What do you 'see'?
What does she say? What does she do?
Ask yourself whatever questions you need answers too as you let your mind build the picture of her piece by piece.
