The greatest athletes in every big sport are White.
Football - Tom Brady
Basketball - Larry Bird
Soccer - Lionel Messi or Cristiano Ronaldo
Baseball - Babe Ruth (he was White) or Ty Cobb
Boxing - Harry Greb
Golf - Jack Nicklaus
Hockey - Bobby Orr or Gordie Howe in my opinion, many say Wayne Gretzky
Tennis - Roger Federer
MMA - Georges St. Pierre or Fedor Emelianenko
The only sport that is debatable is basketball. Negroes often have proportionately long legs and fingers, which gives them an advantage in that sport. But choosing Larry Bird as the best of all time in basketball is better than claiming P.K. Subban is the best in hockey! Subban would not be in the top 500 best in hockey.
Those are all good choices. It's almost impossible to pick the "greatest" in a sport. What constitutes great to one person may not to another. If I had to pick "greatest" I'd pick someone that towered over their sport.
Football: I don't think Brady has towered over his sport but he is clearly the best winning QB in a very competitive Era.
Baseball: obviously Ruth towered over his sport, one year hitting more HRS then the rest of the league combined. Cobb in his Era as well. Mantle was kind of a Brady of his time, the best player who was also a big winner. Mays was probably the best 5 tool player, and Aaron was very good for a very long time.
Boxing: a lot of people would say Ali, but he was not that dominent, Klitchko or Marciano did tower over their sports for a while. So did Tyson but not for very long.
Golf: Nicholas for sure, Arnold Palmer, Woods as well. Very dominant players in their prime.
Hockey: not Orr, too brief a career, Howe was sorta dominant but really it was the span of his career that stands out. Gretzky for sure. Many years of leading the league and shattering records.
Basketball: Wilt Chamberlain was "Ruthian" in his dominince for a while 100pt game, stuff like that. Jordan was clearly the force in the game when he played. Bird was very good but not like those two.