That's literally a fact though?
Races aren't a thing, the race is human. Unless English has a weird definition of race that doesn't mean species, well, there are no races.
Everything that makes the "races" different is just small adaptations for better survival examples including Stereotypical "squinty eyes" being better for snow and fuller lips being better for extreme heat. It's very like different kinda of dogs or cats and such. Not big enough to warrant different species. If anything realistically it would be easier to start classing different breeds different races of whatever species than to try and the other way around.
There is ONE race, humans
Races aren't a thing, the race is human. Unless English has a weird definition of race that doesn't mean species, well, there are no races.
at least from an evolutionary standpoint