It seems to me that the whole concept of cultural appropriation is properly answered with the old cliché that "imitation is the sincerest form of flattery".
Characters in works of fiction are, by definition, fictional, and so have no need to be faithful to real [members of identifiable group]. Further, humans are variable. A character may be described as an extremely atypical [member of identifiable group] but still be entirely realistic. I would hope that authors are not expected to be bound by stereotypes, even flattering ones.
As far as sacred symbols are concerned, as an atheist I reject the very concept of "sacred"; native sacred symbols are no more exempt from ridicule than those of any other religions. 
As far as displaying skeletons is concerned, they're bones. It doesn't matter if they're Eskimo bones, Caucasian bones, Indian bones, or fish bones, they're just bones. Humanity is lost with death. Bones have no rights.