For years, George Lucas has claimed he came up with the idea for Star Wars while he filmed American Graffiti. Citing there was not a modern mythology in the current culture of the early 1970’s. Basing it around the idea of The Hero’s Journey or The Monomyth, devised by Joseph Campbell.
Or that he had the whole Star Wars saga planned from the start. The most vocal critic of this claim being Gary Kurtz, the very producer who worked with Lucas on American Graffiti, Star Wars, and The Empire Strikes Back. He mentions Star Wars was originally supposed to be a standalone film.
In fact, the film was originally devised as a 70’s era remake of the old Flash Gordon serials from the 1930’s and 1940’s. Yet King Features Syndicate (the owners of Flash Gordon) wanted too much money for the film rights. So he had to create his own modern day space adventure flick from scratch.