If thats the case then all the good tunes and songs are received by "accident".

Sorry but I do not believe that the great music and song I know has come down through a sort of "leave a monkey with a type writer and it will eventually write Shakespeare....". To me the more likely process is that talented singers and musicians rework and invent tunes that others on hearing them are inspired to play.... pretty much what still happens in fact today

Having said that I am sure misheard lyrics, part remembered tunes etc.. all play a part in the passing on.