Rock and roll was a new way of saying "rhythm & blues" because a lot of white kids couldn't buy R&B records because their parents didn't want this jigaboo music in the house. So Freed just redubbed R&B under a new moniker.

The term itself is rather older than Freed's Moondog show. Hell, Betty Grable was already known as "The First Lady of Rock and Roll" and the Boswell Sisters did a song called "Rock and Roll" back in the thirties. Wild Bill Moore already had a big hit called "We're Gonna Rock, We're Gonna Roll" in the post-war forties.

To me, the first real rock and roll was Elvis or whoever was the first to record blues combined with hillbilly because that was something new--rockabilly. Doo-wop was a type of R&B that blacks sang that descended from what they sang in church. Whites picked up on it. Gene Vincent was the first that I know of to really combine rockabilly with doo-wop. So it evolved quickly through the 50s and culminated with Eddie Cochran's "Somethin' Else" that was a totally new style. It wasn't rockabilly but had a hard-driving beat. His girlfriend, Sharon Sheely ("Poor Little Fool"), arranged it that way because she got the idea from listening to Little Richard. The drummer for Richard was Earl Palmer (who also played on nearly all the Fats Domino records including his earliest in 1949). Palmer played the beat for Eddie who realized what Sheely was aiming for. Eddie overdubbed himself on bass guitar and guitar with Earl on drums and that's how the song got made. It prefigured hard rock just a few years down the road.

Eddie's nephew, Bobby Cochran, was inspired by his uncle to take up guitar and wound up playing for Steppenwolf and the Flying Burrito Brothers (he's not the co-author of "Somethin' Else", that Bobby Cochran was Eddie's older brother).

So rock and roll was a term that hung on an ever-evolving music so that 10 years after that, the music was unrecognizable and changed again in another 10 years.