And yet this is what racism in Hollywood has looked like for years. Seeing the one color of green has left a tradition of favoring one color of skin, which is white. It is imo racial insensitivity. Compared to fantasy movies based on European worlds where they're very sensitive to everybody being white like in the book/show--sometimes even they need to be whatever nationality they were.
They took a risk and hired a nobody with no experience for the title character and are trying to save their asses by putting experienced 'names' in the other roles.
They cast the movie with who they wanted to cast, which originally was four white actors, some of whom had been in Nickelodeon shows but were hardly big names. Jesse McCartney was later changed to Dev Patel and the Fire Nation then mostly cast as Indian. The Fire Nation being the bad guy nation fighting the others.