This is by definition not something a historian would focus on, as this is prehistory. An archaeologist would be more likely to have information.

That said, since it was brought up, the ‘Solutrean hypothesis’ about the first people in the Americas is widely regarded as a crank theory with no solid evidence behind it, which has had legs mostly because it appeals to white supremacists. Why? Well, it posits that ‘Europeans’ were in fact the original settlers of the Americas, so white people can claim to be the original natives while ‘Native Americans’ are the invaders and interlopers. Aside from the theory having virtually no evidence behind it, it also ignores the fact that Paleolithic humans in southern Europe probably were not ‘white Europeans’ as we know them today, in the first place. It was far too long ago for those kinds of ethic groups to be relevant, never mind all the migrations and mixing that occurred between then and now.