I can't help but equate John Mayall with "Music" on the level of Juilliard for the Brit groups of the 60's. And without doubt, the Brits were the most influential factor of all in the 60's. Can we say "Redefinition?" Indirectly, his presence set the stage for final lineup of "The Yardbirds" with Clapton leaving them and Jimmy Page taking his place which ultimately resulted in Led Zeppelin.
The FUNNY thing is that Mayall had NO INTENTION of catapulting Rock into such a frenzy! He just wanted to play Blues and play it RIGHT. <LOL>
I have read so many books on the changing times of the 60's besides having "been there" myself. There is just no doubt that it was the decade from 65 to 75 that pretty much defined the music that I like. There have been "sub divisions" like "Psychedelic", "Metal", "Soft Rock", "Country Rock", "Punk", and all the others but mostly they are refinements of the "ROCK" that evolved from the Sock Hop type rock and roll back in the 50's and early 60's.
Besides pure Blues (Delta, Chicago, Texas, etc.) about the only other two genres were "Soul" or "Motown" and Country. I remember clearly (or at least foggily) going to clubs in the late Sixties where Soul bands performed until 1am and then the Psychedelic bands took the stage. This was in Dallas and after 1am, they stopped serving alcoholic drinks and let in anyone over 18. Soul was very popular...Sam and Dave, Aretha, James Brown...all that Motown and Soul sound. But after 1am, the music was Jefferson Airplane, Strawberry Alarmclock, Grateful Dead, Canned Heat and weak covers of Hendrix tunes (About the only thing most of them could do justice to was "Wild Thing" but that didn't stop them from trying!)...the "heavy" stuff.
I'm not sure quite where RAP came from. A lot of rhythm there and a lot of rhyme, but I could never get into that scene. I guess my tastes were formed and frozen by the end of the 60's and RAP and Punk and Industrial and even the Shredders and Heavy Metal came in after I'd gotten to the point that I could really appreciate them.