Of course Elvis wasn't the first rock star!
I mean, say what you will about Bill Haley, but he was on the scene before Elvis. There were many others.
Elvis was, however, rock's first superstar. There's the difference.
People give Elvis credit for many things he did not do: starting rock'n'roll is but one of them.
And the article has at least one inaccuracy: Jimi Hendrix died at 27, not 28!