The 747 was actually an afterthought by Boeing. In the late 1960's Boeing was going to build supersonic planes for passenger travel and the 747 for cargo only. Then they got wind that the Brits and French were building the Concorde and that ended the supersonic planes. If I remember from reading some information, the head of one of the airlines said he wanted to move a lot of people over long distances, so the 747 was converted to a two aisle passenger plane. And the rest is history.
Beautiful plane and really great flight path.....