Ezra has blue hair, is there any good reason why that can`t just be a valid human hair colour in the SW universe? There are lots of alien species, can`t there be lots of human ethnicities in Star Wars too, different or more than on our earth? Black skin, blue eyes and red hair? Sure, why not? That can be a valid ethnical appearance in the galaxy! Why should humans and races look like they do on our earth? Why can`t there be more?
I know there isn`t any one true answer to this question. But how would you handle it in your game? Could someone play a human with bright red skin and natural purple hair if they wanted to, saying it was just a human variation?