There were pre-Beatles, influences (Buddy Holly and the Crickets, Roy Orbison, Johnny Cash) but none had that "bam" impact on the world at that one time. You have to look at why people picked up instruments and decided that writing their own songs, playing and singing them was the thing to do. The Beatles, definitely got that started. No Rush if there were no Beatles.
Led Zeppelin is derivative and yes, overrated. No question though, that Led Zeppelin set the blueprint for 70s hard rock. Had their been no Led Zeppelin, there would still have been a Rush, but I don't think you'd see a band have the courage to try different ways of performing, acoustically, electric blues, progressive leanings were it not for Led Zeppelin showing that you can do all of these things and still be macho and still get the ladies.