Rock around the clock by Bill Haley was one of the first rock and roll songs in the early 50’s
Ike Turner's Rocket 88 was recorded in 1951 and is considered the first rock n roll song. Bill Haley came four years later. There was a LOT of music in between. But it wasn't being played on mainstream segregated radio stations. Early rock was passed around on 45-rpm discs. "Hey man, you have to listen to THIS."
Take 1952, for instance:
Hound Dog: Big Mama Thornton
Lawdy Miss Clawdy: Lloyd Price
Good Lovin': Bobby Bland
Reelin' and Rockin': Fats Domino
We All Got to Go: Joe Hill Louis
This was what I consider the foundation of the genre. The only reason rock didn't take off earlier? Segregated radio.