Likewise, measuring the ability to jump, sprint, sing, dance, eat watermelon, there is more variability(difference) amongst blacks and amongst whites than between whites and blacks.
To put that another way: There is more intra-genepool variability than inter-genepool variability
This applies to many other things. There is more variability in the quality of the trucks in Mexico and more variability in the quality of trucks in the US than there is variability between Mexican trucks and US trucks.
You are quite correct. However, I fail to see why the point is relevant.
There is much greater variability in strength and athletic ability, for example among women and among men than there is between the two groups.
Does not change the fact that men, as a group, are able to beat the crap out of women. That there are extraordinarily exceptional women who can beat up most men, and men who most women could beat up, also does not change the basic fact.
* in the statistical sense.
Granted the “Bell Curve” for each group. That is not the point. The comparison is between groups.