The point you're missing is that you can't judge how good the sexes are at a sport relative to each other when you segregate that sport from one of the sexes from a young age. We don't really know how well women can be at football, as we typically don't let girls play it past the peewee level, if that. You bar girls and women from playing a sport, then act surprised when they don't do well at that sport. In fact, you point to that as proof of women's supposed inferiority.

You can technically open up the NFL to women athletes, but your asinine "just saying" ignores that this proves nothing. If women are barred from competing at the middle school, high school, and university level, of course no women are going to be able to make it in the god-damn NFL. You deny them the opportunity to develop the skills, and then you cite their lack of skills in adulthood as proof of women's inferiority. You discriminate against them and then cite the results of that discrimination as proof to justify it. It's like how in the pre-Antebellum South they justified slavery on the supposed intellectual inferiority of black people, and that same time made it illegal to teach them how to read.

Additionally, as others in this thread have noted, it's not so much that "men are better than women at sports" as it is "we value sports where men have an advantage, and devalue sports where women have an advantage." An example mentioned was that we have sports where people jump over high hurdles, but we don't have a competition where people crawl under them. And pretty much the only sport that is widespread and takes advantage of the superior flexibility and movement skills women have is gymnastics. But many other sports could be invented and championed that would similarly disadvantage men.

In an alternate world, the belief would be that men suck at sports. If our sports valued flexibility and efficiency over brute strength, women would wipe the floor with men. Male athletes would be derided as useless bricks that can't move with any finesse, completely unsuitable for any serious sports.