Humans learn by copying. The process of creation is one largely of cutting and rearranging all the stuff we've copied.
In the 30 years since its release, A New Hope has been picked apart by fans and critics looking for antecedents in the story and the visuals. A long list of those are available at many fan sites. I've made a humble list here at Amazon.
If you make it all the way to the bottom of the list, you'll find the one item that doesn't fit the set, a CD in a list of DVDs. George Lucas wasn't the only one who borrowed ideas in cooking up Star Wars. Have a listen to Austrian composer Erich Korngold's, theme for the 1942 film, King's Row and you'll hear something entirely familiar.
What I'd like to know is, has Williams ever acknowledged riffing on Korngold? And, who was Korngold copying?