Why is it called football?

Well you kick the ball so that comes under football. Though theres 3 footballs. Soccer (football) American Football and AFL (football)

American football was started in 1879 with rules instituted by Walter Camp, player and coach at Yale University.

One precursor to Walter Camp's influence was William Ebb Ellis, a student at the Rugby School in England. In 1823, Ellis was the first person noted for picking up the ball during the soccer game and running with it, thereby breaking and changing the rules (but not the name) of the game.