As I try to say, George Lucas had a lot of good, talented people helping him with Star Wars and the OT as a whole (Ralph McQuarrie comes to mind). Part of his problem is the way he's tried to overshadow their work and glorify himself by comparison. The other part is how he has tried to dismiss and destroy what others have done.

That said, Lucas was more talented in his younger years, just not as much as people say. There was a mix of many factors. Star Wars was a success of luck more than anything.