Most great SF properties were build on a haphazard world building. Many of them were built up in pieces in story after story. In the case of Star Trek it was by many different people adding pieces to it. Star Wars had early input from Alan Dean Foster (Splinter of the Mind’s Eye was the first idea for a sequel) and Brian Daley (some of his terms have become movie canon). Some things from the Marvel comics got used. That was the first place we saw speeder bikes. So while many think George did a lot of that solo, he didn’t. There were a lot of ideas swirling around and some of them ended up in the films. The PT probably had more influence from the EU as it developed later. It definitely had influence from the West End RPG. And to be fair, all the EU had input from GL, but it was fleshed out with ideas that did not come from him. Many were the necessity of the story and the writer that created it. The PT is just the first time that the film’s stories were developed and fleshed out by other writers. And even Johnson was working to a story arc. He didn’t have to worry much about world building because he was writing the middle story and could focus on character development (and contrary to some opinions, the movie is full of character development).

What we do know that Kennedy and Abrams started from Lucas’s treatment and the put them through the normal story development process to take a rough idea and expand it to a workable movie trilogy. We know that some of Lucas’s ideas made it through to the final films. A lot in the movies is new and comes from the expansion of the story and new directions that they took. George would have made similar changes had he done the story development himself. We would have gotten something very different, but I bet it would have been as divisive if not more so.