I suppose, if you consider races to be analogous to breeds, except a lot fuzzier because no one other than the egyptian pharaohs and european nobles were trying to create “purebred” human varieties (and even then, only among themselves), then you could semi-reasonably claim “biological reality”. However, by that standard there are at least 3 “white” races and 7 “black” races, probably more depending on how/where exactly you draw the borders, because, you know, it’s pretty darn fuzzy. I mean, have you even met a human? Quite a lot of them would fuck anything vaguely mammalian with two legs - and occasionally that’s not even a barrier - so you can’t expect them to neatly cluster into specific “breeds”. So there are quite a lot of “mutts” running around, especially in the modern world where long-distance travel is common, which is probably a good thing because having an ancestral variety tends to result in being healthier on the average… not that any of this should matter, except maybe to geneticists and epidemologists.
“Races don't exist because Whites are the only humans." This is just plain incoherent. All humans, regardless of race, are members of the species homo sapiens. There’s no way that can be true without throwing out both genetics and cladistics. If you replace “humans” with “persons” then it could philosophically be true (if you subscribe to a superficial garbage philosophy where it makes sense) but it’s not legally true anywhere in the world today. If your philosophy demands such laws, good luck with that.