Regarding pygmies, they are a different cluster from the highly homogenous cluster of Niger Cordofian from which current African American population in America descends. From the article I cited: "High levels of heterogeneous ancestry (i.e., multiple cluster assignments) were observed innearly all African individuals, with the exception of western and central African Niger-Kordofanian speakers (medium orange), who are relatively homogeneous at large K values(Fig. 5C and fig. S15).)".
I see you are also a bit disingineous if you dont think there is a high correlation between athletic abilities and genetics. Gimme a competent geneticist, 200 hundred genomes of 15 years old boys: 100 African Americans and 100 Guatemalans, shortest dudes in the Americas. I am pretty confident that I can pick 2 teams of 5 kids just by their genome and pick the correct winner of a basketball game between them with high probability. Yeah I cannot predict individuals outcome(yet) but population wise I think it is not a crazy stretch.
On the other hand I see your point that there is no crystal clear boundary between any human group, but if you take that position you have to be consistent with it. What I mean is that I assume you are not happy with an universal definition of black (I can understand and even agree with that). But then you are forced to admit the concept of White privilege is vague too. Same reasoning. You could say "White" is a cultural concept, but I could say the same regarding "Black" so we are back to part 1.
Again I suspect we have more points in common that differences regarding this topic, I just wanted to put out there some considerations.