I have known the song for >60 years, and can no longer remember how I learned it, but at a guess it was in circulation in my high school, which had a strong folksinging tradition, and I must also have looked it up in print. The words I know are the Lomaxes'. However, we (I?) customarily repeated the first verse at the end, to a somewhat decorated tune (solfa, scale is DRMFSLTdrmfslt^, dots mean continuation for half a beat):
d.d.m.s.........s.l.....l.ls......
m.l.....mmrd....SLDmrd.L...........
dd^.........l...sm..............
r.......L.d.........
(more or less).

Even at the age of (say) 14, I had no trouble interpreting "Norah's" as "Noah's", without an explanation. I also had no trouble believing Lomax's story, but I was & am naive.