Rav Avigdor Miller says that Adam’s genetic material was
diverse enough to eventually produce all of the races.
You should note that … humans who look “different” … produce children with characteristics from both parents, which further supports my argument that physical differences are negligible.
I don’t think that’s a good argument. Animals from different
species also produce offspring with traits of both parents –
that doesn’t mean that there’s no real difference between the species.