Well, The Beatles of course have been "The BIG BANG" of Pop Music but the story is quite more complex. Rock n' Roll was rooted and "invented" in the USA and spread over the world. No doubt about it, agreed? The British added a touch of their brand of influences i.e. "Skiffle" and Pop and the so-called "Beat/Mersey Beat" was created and played by bands wearing "uniforms" on stage like the early Beatles, The Searchers, The Swinging Blue Jeans and and and ... Some others added a touch of Rhythm & BLues to that R'n'R, like The Pretty Things, The Animals, The Yardbirds, The Kinks and and and ... the Americans re-imported all that stuff and took it to the next level in their GARAGES in the years 1965/66 and all this went into the year 1967 - the "Big Bang" of Psychedelic & Hippie stuff from "The Summer of Love" in San Francisco AND all this was re-imported by the British again and turned into that very popular (at least nowadays) "Freak Beat".
I hope it's not too confusing but I tried my very best