"race" is a social construct; there's no gene or cluster of genes common to all blacks or all whites.
Sorry to disappoint you but races do exist. The definition of race does not require a specific gene present in 100% of its representants or exclude having broad differences within a race. When you say there is "more genetic variation between two black people from different African countries than there is between a black and white person" you forget one thing: How you can quantify these differences? It was only possible because first YOU subgrouped the people into those races you later deem as non-existing. A logical flaw.
They exist, but this of course does not say that one is better than the other.
Denying their existence is like denying that there are women and men and that gender is a social construct. Scientifically hopeless.