Hans Christian Andersen wrote The Little Mermaid in 1837. It's not "a folk tale" or a myth. Her skin is described as translucent green. Her hair color is never mentioned. She is in constant agony with every step she takes, the prince treats her like a pet, then marries another.
Not all books from diverse authors need to be inspired by their own cultures. Seeking diverse voices only for the books with “traditional aesthetics” is unfair. Sometimes we want to create original worlds too. But that doesn’t change the fact that we are still v much marginalized