Really, the more you think about that theory, the dumber it gets.
You sure could! Why wouldn't you? Do you reject the concept of evolution via natural selection in all species or only humans?
It would actually be quite the story if the races were somehow identical in all of these traits.
Both of these positions are untestable. One, however, is extremely likely while the other would be a miracle even in the wildest fantasies of the wokest progressive.
How would you explain how geographically distant groups in radically different conditions could, over millennia, converge on all of the exact same non-visible traits without even minor variations? I truly can't imagine a way that this would be possible aside from the infinitesimally unlikely product of completely random chance.