@bdp24
Both Beatles and Stones, like pretty much every band that ever existed (as you noted, The Everly Brothers didn’t invent sublime two-part vocal harmony and had a wealth of recordings featuring such preceding them) started with covers, and generally mimicked their idols.
Their clearly-inferior-to-the-original-version covers
(although the Beatles’ August ‘63 live BBC performance of ‘Don’t Ever Change’ by Carole King/Gerry Goffin - the duo that wrote ‘Crying in the Rain’ by the Everly Brothers, the group for whom ‘Don’t Ever Change’ was originally written - is outrageously good, identical to the melodically-complex/difficult vocal harmony studio original by the Crickets…only live…)
are a mute point.
Even then, I would still put the earliest Beatles compositions, i.e. “P.S. I Love You,” “Ask Me Why,” “Love of the Loved,” “Please Please Me,” all from ‘62, to say nothing of the dozen-plus knockout originals in ‘63 - yep, that early -
(the likes of which include classics as non-album singles, the best originals on their two ‘63 LPs, and the handful of stone-cold gems written for other artists in ‘63, i.e. ‘Bad to Me,’ ‘I’m in Love,’ ‘I’ll Be On My Way,’ - Paul actually wrote ‘World Without Love’ when he was 16)
up against any pop group of the time in ‘63.
Obviously, mid-‘60s-to-early-‘70s Beatles/Stones is canonical.
Everly Brothers wrote a handful of great songs, but their catalog is non-original dominant (particularly by the Bryants).
The fact that one guy, Clapton, desired late-‘60s pop to be more “roots oriented” is nowhere near some “last word on music,” is by no means an expression of anything resembling “universal truth” on where popular music “should have” been heading.
Maybe there were a ton of music fans/artists in the ‘60s whose minds were blown by “Tomorrow Never Knows” and Revolver, by Pet Sounds, and the innumerable records then that created something entirely new, innovative, and as far from “dudes regurgitating rural Americana” as possible.