So since everything else came afterward, you conclude everything else was derived therefrom?
Yep....pretty much.
Rock and Roll had only been around for less than 10 years and was dying as fast as you could say "Elvis is outta the Army....and he's NOT the same".
Yep....I'm saying without them, Rock and Roll would have never have matured into "ROCK", there would have been no Who, Stones, Traffic, or Steely Dan etc.
Without the lovable mop tops, The Beach Boys would have continued writing "Little Duce Coupe" and Dwayne Allman would have never picked up the guitar.
(and wouldn't that be a shame)