The chanties were very different beasts to the mainly ballads sung on shore and in the foc's'le. Totally different conditions. A worksong is a tool, not a piece of entertainment. Nobody I know of (well okay one, who keeps distorting everything anyone posts) would suggest that ordinary people did not create songs, they obviously did. The situation in nineteenth century England was that they were swamped with mass-produced songs just like today and the few locally produced songs in rural areas didn't stand much of a chance of becoming part of oral tradition. Or if they did only a few of the them survived to be recorded in oral tradition.

What do you mean by 'communal songs'? the chanties weren't communal in the sense that it was one man making it up, the chantyman. The crew knew the chorus and tune, but didn't take part in the creation as far as we know.