Sort of yes.redhead is ethnicity?
Natural red hair isn't that common, because both parents need to be a carrier for the gene to produce a child with red hair.
And because it's almost only available to caucasians, it kinda makes them a sub-species of them.
I that wouldn't be the case, more redheads would exist and probably areas/communitys with a lot of redheads would be there too.
But there are a lot of different theories/opinions around and there probably will be some people around even here who will tell me how wrong I am, but thats not the place here to discuss that.
As I already said, I chose those words, that the everyone would understand what I mean. If you are that picky, then for example "black" or "white" aren't the correct words either.