h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

hmmm.. no he didn't
He actually started out out as a backing singer for The Wailers.
If you are looking for the true originators of reggae you should look to the handful of musicians (such as Sly and Robbie) who actually are responsible for the Jamaican sound.

Actually,you need to go much further back than Marley for the origins of reggae. If I'm not mistaken it was Toots who coined the name Reggay and later it was modified to later Reggae.
As for its first appearance as an identifiable musical form.... It would involve some interesting research.

Its certainly way before Sly and Robbie, they developed a particular brand/style of reggae as did Marley and the Wailers.

Marley was a solo singer before he joined the wailers and his first record I think was "One Cup of Coffee".

Reggae came from a number of things, jamaica already had music styles like Mento + Calypso which played a big part in the making of reggae, the jamaicans main influence where soul and R+B artists from America. Jamaicans used to be able to pick up the American radio stations and this had a big effect upon the music that was played in Jamaica at the time, the locals would also get most of there records from passengers on man of war ships that used to sail into the ports in jamaica.
So reggae was formed from a mixture of the music styles that already existed in jamaica and the american influence of R+B, some of the early reggae artists where The Skatalites, Toots+The Maytals, Jimmy Cliff. The Skatalites get alot of credit for being one of the first reggae bands and they invented alot of the riddims you here today.
If you ask the Reggae artists about the origins of reggae, u will usually get different stories as they all seem to have different ideas, but there are 2 or 3 versions which all seem feasible, bunny lee will tell you that the word reggae came from a Dance known as Streggae, and this is where the word reggae came from as thats what they danced to the music. Others say that the first time the word reggae was used, was on a song title.