Phil
I use the word chanty to refer to Dana's examples simply because at least some, if not all, of them are referred to as chanties later on.

So no, not agreed. These specific songs, some from even earlier, are referred to as chanties later on. Okay, so we can say they eventually became chanties when they were used aboard ship, or even by the stevedores with a 'chanteyman'. I'm personally happy with the idea of 'proto-chanties'.

I have had 'Two Years BTM' for many years but the question still stands, does the Seaman's Manual have anything relevant? This I haven't seen.