Hello my friend Carcharias and I hope you are well.
I think the answer to this question is like the easiest in the history of mankind (I love the dramatic tone lol)..............Simply because they live in a richer country, they have way better nutrition and of course and most importantly, they USE SUPERIOR STEROIDS. Both Tyson and Roy Jones from the ones you mentioned are very well known steroid cheaters. As for Joe Louis, have you seen a photo of this overrated man during his prime? I wouldn't describe him as athletic really. Don't you ever wonder how blacks look so "strong and athletic" in the NBA nowadays, while back in the 60's and 70's these tall skinny with an Afro black ball players reminded Kenyan long distance runners? Superior steroids is the clear answer.
Is it a coincidence that Jamaicans who won a medal every now and then, in the last two Olympics have won so many medals, now that the accusations getting more and more against scums from the USA, who used to feed black American athletes (Conte among others) now feed these steroids to Jamaicans?
Why most British, French or Dutch blacks don't look so big or athletic as black Americans, have you ever wondered? Because no "chosen" people cover their dirt in those countries and blacks there can't use excessively the steroids black Americans use..........Well I forgot of one, Dutch Superman Overeem..........Wait a minute didn't get caught for steroids too? You get my point!
Blacks Americans have been used in specific sports, like lions and horses were used back in the Roman era, only so some "chosen' managers and promoters will get richer and richer, while in most cases the "super athlete" ends up ill (Ali), broke (too many to mention) or dead (What's the name of the woman who broke the record in 100m?)