Well, duh!
Peter Pan is the creation of an English playwright with all kinds of fantasy characters in the story - pirates, fairies, a dog that is a nanny etc. etc.
It also has Indians - not native Americans but the kind of Indians that exist in children's stories.
If only native Americans can play the Indians, then who do you suppose should play the fairies? And the mermaids?
I do believe that Nana is usually played on stage by a human!!! Imagine that.
What ethnicity should Peter Pan be? Is he English because J M Barrie was English and should he only be played by an English boy?
Could he be a generic boy of no fixed ethnicity? We don't know anything about his parents so maybe he could be played by a Chinese lad, or perhaps an Australian because our men never grow up either.
I can see why there is a fuss about this but I don't think it has much validity.
Better to push for more parts for native American actors in all sorts of roles, not just ones where the ethnicity is specified.