Well, take away all the shit like ping pong and synchronized swimming, and we disproportionately win the most medals even with the vast majority of our best athletes pursuing professional sports. Take any international sport that we actually participate in to any degree like basketball or track and field and we completely fucking dominate. Is this even a question? LOL
We would fucking obliterate Europeans in soccer if that's what our best athletes played, but soccer is sorta what you do if you suck at Football in the states. Like most high school football teams in the U.S. could beat their soccer teams with a few weeks of practice.
Yes big black dudes exist in other parts of the world, but there's nowhere on the other side of the pond like Detroit or New Orleans were pretty much every public school has produced multiple world class athletes.