It's not a racial question at all and I think anyone who becomes offended is putting WAY too much into it. I think your question is intelligent and I commend you for being straight forward in "just asking".
Part of it is culture. Part of it is genetics. Its just facts.
The list you have here is just a very good example of fighters using skills that are thought of as indigenous to Black fighters. People don't think in the Neanderthalic ways like before. If I have a White fighter with crude skills, I would certainly try to teach him more about defense while enhancing his current skills.
It's a fact that there are SOME minor differences between beings of different groups. These differences don't make "Person A" better than "Person B". We, as humans, are just built differently. Most differences are only minor.
Look at most Asians. Their legs are considerably shorter, in relation to their overall body height. This is the reason they excel in martial arts. Its what I like to call the "broom handle theory". LIft a broom by it's tip and see how heavy it becomes. Now take a Black martial artist with longer legs. His legs take up a greater percentage of his overall body height. Hence, the reason he must exert a bit more effort to throw kicks.
AGAIN< these differences are only minor.
White of European descent are Usually better swimmers. This is because their chest cavities are a bit wider, allowing for more air in their lungs. Their muscle density is just a bit lighter, allowing them to float better. This is also why many White fighters tend to have greater stamina.
Black fighters normally have longer legs and arms. Their muscle density is a bit greater. Take a Black man and a White man of the exact same size, if you can find two such people, and you will see that, ON AVERAGE, the Black man will be a bit heavier.
This is also why Blacks are Usually faster runners. A Black man at 6ft tall Usually has longer legs than a White or Asian of the same height.
NONE OF THIS means that Blacks can't be good swimmers. I know many who are
NONE OF THIS means that Asians can't play basketball or that all are good at martial arts. I know many exceptions
NONE OF THIS means that Whites can't jump or box. I know many who can.
Today, many trainers teach their fighters the strengths of many of the older fighters. This is why Joe Calzaghe can box as he does. It's mostly in the way of thinking and being a bit more open minded.
Your list is a great example. It's more in the way of thinking.