I get confused when it comes to fashion, as there are only so many ways that hair can be worn, and so many styles of clothing, and young people will always want to look unlike their parents, so are almost certain to look outside of the 'norm', whatever their culture. Traditional dress is, in most cultures, kept for festivals and so on - I don't even know what a traditional English outfit would look like, although the other UK countries have kept their national dress.
Fashion seems to me a bit like knitting stitches, where I am on safer ground
. I think it is generally agreed that nobody can copyright a knitting stitch, as it is impossible to prove that it hasn't been knitted before, but when a number of stitches are put together in a particular way, and made into a pattern with shaping and so on, the pattern can be copyrighted.
Sometimes fashion trends follow films or TV series - I have seen a fashion for the hairstyles used in Vikings, for instance. I have no idea how accurate the costumes and hairstyles are, but they may well have been worn by people all over the world at one time or another, and some are not unlike the Native American ones. When you are looking at cultures that spanned hundreds of years there is sure to have been some overlap, by accident or design.
I'm not sure what point I'm making now - I was responding to the question about the Mohawk photo
.