That, and transforming Lucas into some kind of visonary driving force behind ILM, as if Lucas was behind the invention of special FX driven movies, for the big turns the FX industry took, or personally responsible for the technical innovations (he's little more responsible for pushing ILM's limits than the rooster of directors ILM worked for over the years, key ones including Ridley Scott, Cameron). Ironically, Lucas has held back ILM several times (most notably by forcing them to abandon extremely innovative forays into computer generated FX. Lucas pulled the plug on that and sold their first computer division to Steve Jobs. According to Lucas, miniatures and models were the way to go and CGI was for animation, computers wouldn't be used on a large scale for live-action movies' FX for maybe decades... Oops.. a few years later, ILM had to buy licenses to innovative tools developped by other companies and hire people who worked there to catch up before emerging smaller companies, for example Cameron's, took a lead, eventually closing their outdated practical FX divisions by the time Lucas finished using their services for his prequels)

It's mostly in terms of aesthetics that Star Wars was a landmark. Lucas and his art directors reinvented how spaceships and robots ought to look like. That was influential, though the guy most directly influenced by this (Ridley Scott) soon became even more influential in this respect (with the art direction of Alien and Blade Runner).

At the time Lucas made ANH, Hollywood was already sitting on tons of projects for SFX heavy movies. The economy and the turn the American directors had taken (toward a darker, more European influenced cinema and smaller scale productions) in that decade had slowed down the expected arrival of "space conquest" influenced entertainment cinema.

By hiring the top crafstmen in each craft of SFX and stacking them in a garage as a company, Lucas was able to make ANH with shoe-strings. It's not the movie as such but its success (combined with that of CEOTTK by Spielberg) that convinced Hollywood to greenlit several projects on hold. But Lucas didn't exist in a vaccuum, and unlike several others of his generation who were dreaming to return to big productions, for Lucas SW was just a little trip for nostalgia's sake to the movies of Harryhausen, the serials like Flash Gordon and Buck Rogers. He was one of the young directors most influenced by Europe, Truffault and Tarkovsky and so on. And Kurosawa whom he idolized. He was foreseeing a career as a director of critically acclaimed obscure movies... so much for that, he just didn't have the talent for it, and he couldn't direct actors if his life depended on it.

There were other directors/producers far more important than Lucas in the big return to big productions, among them Coppola, Spielberg and Ridley Scott.