A lot of smart, talented people made 'Star Wars', film has always been collaborative, the auteur theory was an exercise in self-publicity by film critics.
However (and if this conversation continues then it should probably have its own thread) without Lucas there is no 'Star Wars'.
It came from his head, the product of a childhood sent watching old serials and souping up cars. It's Flash Gordon meet King Arthur in the wild west with oily spaceships and flashing lights because that's where Lucas' mind was in the early 70's.
He never hesitated to bring in other people and other opinions but without him it really wouldn't have been 'Star Wars'. Someone else might've come up with a new space adventure or maybe remade 'Flash Gordon' (as Lucas had wanted to) but this combination of elements came from one man.
I believe I said the last time we talked about this, you only have to look at all the ripoffs to see how easy it was to get it wrong.