this art is so fundementally flawed on literally every level i genuienly have no idea how to criticize it but ill try
1- dont use the fill tool and if you do PLEASE color in the white spots left behind
2- clean up your line art, I shouldn't be able to see cass' head through her hair
3- cool it with the airbrush it looks awful
4- look up some anatomy references and learn to break down the body into basic shapes
5- look up a skeleton and break it down
6- put more effort into the backgrounds, her feet aren't even on the ground
7- idk what's even going on with the guy in the back
6- learn proportions, cartoons dont have to look realistic but its good to have an understanding of how real world bodies look before trying to exxagerate them

overall I can tell you are very young so please dont let this discourage you from drawing in the future. you have the potential to be amazing if you work hard enough, ive improved tremendously in the last couple years and i still have a ways to go
if theres any advice i can give you its to keep practicing and dont skip the basics, guidelines, anatomy and proportions, references, color theory, caricature
all your friends buddy
just keep going