The specifically American character of the mythology has to do with the violent nature of the game. Not only does it dramatize the myth of creation, it also plays out the myth of American origins with its violent invasion of regions and their settlement. To a certain extent, football is a contemporary enactment of the American frontier spirit.
From "The Superbowl Culture of Male Violence" by Eugene C. Bianchi
...this great national sport, which claims the devotion of a significant percentage of our population, mirrors in a ritual way some of the worst characteristics of our culture. ... it interlinks four qualities that drive the American violence machine: physical brutality, profit-maximizing commercialism, an authoritarian-military mentality and sexism.
... I have come to the conclusion that the fundamental evil from which the others flow is sexism. The basic way by which the male in our culture establishes his sexual identity is a prime source of exaggerated aggression in the interpersonal, economic and political realms. The problem can be put thus: How are males in our society conditioned to value themselves as persons? What are the criteria of self-worth and social acceptance among American men?