also football can be played in basically any number, from 1:1 to 11:11, which means you can go out with a ball, meet one other kid and play, and random other kids can just join in.

I've literally seen kids unable to speak with each other because of different languages able to join a match :)

I was terrible at football as a kid so it's not like it did much for me, but one cannot deny how universal the game is.

That's true. It's not unique to football (same can be applied to basketball and volleyball and etc.) but it's one more advantage.