Ok so there’s this round ball in the air coming towards you.
You have 2 choices:
a) CATCH the ball (with your HANDS), or
b) hit it with your HEAD
Hands with opposable thumbs are what separates human beings from all other animals. To take them out of a game seems, well, kinda dumb.
You might like one of the other football variations, e.g. Gaelic, Aussie Rules, or their Hybrid form all limbs are in play, no headers ...