Shambles,

A good quality molasses, is almost the same as black treacle. Poorer ones are much like colored syrup.

I like your statement "If a nationality of a song is obvious, in it's style or content, then so be it, but let's not struggle to find one for it, as that may prevent it from belonging to us all."
But I find the origin of songs kind of interesting, not for any nationalistic reason but more from curiosity.
Bert.