Everyone lines up by color/team and the ball, I imagine, is in the middle.
It starts in the middle but subsequent plays start where the previous one ended.
Then everyone starts fighting. Where does the ball go?
That’s not how it works in Football. One team has possesion of the ball and their aim is to get it to the goal. The other team’s aim is to take possesion of the ball for the next play.
Shouldn’t they all be fighting in one pack, with the person who actually has the one ball?
No, an all-out attack on whoever has the ball would leave other players open and whoever had the ball would just pass it to an open player.