Caine made bodies perfectly encapsulating their mind profiles and since he was genuinely trying to be helpful, I think these are meant to be good for them. So here's my speculation on why they are the way they are
Zooble's is obvious - being able to change your body and represent yourself differently depending on your mood is very nonbinarycore. Zooble is also a person who explores different creative pursuits, like art and tattooing and creating drinks, so the mismatched nature of their parts might be about the sort of grab-bag nature of their creative interests
Ragatha - she always wants to be liked, and relied on. So she is a soft doll that is typically hugged by children to bring them comfort. But she's also worried about not being good enough so her body is imperfect. Maybe it's also a reflection on how she doesn't want to get hurt, so she's not able to be broken.
Pomni- jesters aren't just to make people laugh, historically their role was also to keep the king from getting too up his own ass. Take him down a peg. Maybe even vent people's genuine frustrations in a comical way. Which i think fits her perfectly. She's funny, yeah, but she does see people for who they really are, and reaches out to them. It's her introduction that leads to Caine coming down from his throne so to speak, and shes the one who starts with insulting him in ep 8. She's also red and blue, like Caine and his "sibling", so perhaps he sees her as similar to him, he even calls her relatable in episode 8.
Kinger - chess piece, logical, team player, creative, no legs (maybe because he sat on a rolly chair so much) but his hands can reach far from his body, lopsided eyes that maybe represents the different perspectives he can take. Also, fancy on the outside but simple on the inside (really the opposite of how he appears in the show)
Gangle - I find Gangle the hardest to understand. The masks might be a reflection of her bipolar. Her emotions aren't actually limited by the masks, but she seems to believe it is, at least at the beginning. The body might be about simplicity and creativity. Like the beginnings of a drawing. Something she can build on.
Jax - a cartoon rabbit, often associated with girly things, and with a purple and pink colour palette. The adorable room. But, as with all the bodies, it's kind of a neutral body that's really only gendered by clothes/pronouns. And if the nightmare of having the inside peeled off isn't just a nightmare, it could be that Caine gave Jax the ability to change his outwards appearance if/when she decided to come out. Whether or not that's true, Jax has room to play with expression however they want.
