American football is indeed a product of the USA and developed into its current form in recent American history, but the origins of the sport date far back and have influences from across the world.
One of the first official games played that could be thought of as American football took place on November 6th, 1869, in New Brunswick, New Jersey, between Rutgers and Princeton teams. This game was an adaptation of the sport Americans know as soccer with rules similar to those used in London. By the 1870s, the sport had developed into a game more similar to rugby by colleges and was played by colleges like Harvard and Yale.
If you had to attribute the invention of modern American football to someone, however, Walter Camp is the man. Often called the "The Father of American Football," he was a Yale student who played the sport in the mid-1870s and eventually became coach of Yale's team.
He was an extremely influential force on the rules that make up the version of the game that we recognize today. Some of his influence can be seen in the following aspects of the game:
- The change of possessions after failing to move the ball downfield
- The quarterback position
- The Line of Scrimmage