Why is football named football?
Because it is based on a game where a ball is kicked with your feet.
American Football is derived from Rugby Football which is itself derived from (English) Football or Soccer, a game relying much more on the use of the foot
The word football is from the English language a compound of 'foot' and 'ball' and was originally written as two words 'foot ball'. There is an historical definition of the word 'football' being 'a ball game played on foot'. An alternative is in reference to the kicking action of the foot against the ball. No clear evidence exists for the etymology. The Oxford English Dictionary first records the word in 1424 in an act banning the game. The original foot ball game was a ball game played at Shrovetide in medieval England. Other European countries also played Shrovetide ball games by different name which were very similar to Shrovetide football. The game had few rules but specifically prohibited the use of transport. As a result the game had to be played on foot hence the assertion 'foot ball'. All modern codes of football can be traced back to these Shrovetide ball games. Originally played all over England, the game has survived in some isolated places. See the attachment from the BBC regards this years proposed Shrovetide football games in Derbyshire (2011).