The whole "so and so" invented rock and roll is silly and pointless. Hell, the first person to even use the term "rock and roll" was Alan Freed, definitely not black. Just like with the who invented heavy metal, it isn't as simple as that. It was a process developed over time and different regions, with many different influences.
If you listen to the first Sabbath album (which erroneously gets credited as the first heavy metal album), there is more jazz influence than Devils Triad.
And then you have, Zeppelin, Deep Purple, JImi Hendrix, Cream, Steppenwolf, ELP, and on and on, that were just as much a contributing factor to what we now call heavy metal. What about Judas Priest? They could be the ones that truly created the genre, if you really think about it.
In short, it's more complex than sos and sos invented x.