Jobs was in the right place at the right time when personal computing was getting off the ground. Same with cellular telephony. Without Xerox PARC and Motorola wireless collaboration, there would have been no Mac and no iPhone from Apple.
But this sort of thing is true for any innovation - the seeds are always planted from a variety of sources. The PARC's existence doesn't invalidate what Jobs did for the Mac. It's like saying without the Blues there'd be no Led Zeppelin. Okay, but so what?