There definitely is a traditional origin for this song. With some very minor melodic changes, you have an old spiritual first published in the early nineteenth century called variously "Lonesome Valley," or "That Lonesome Valley." Search hard enough and you'll find that most folk, country, blues, and, by redaction, even pop and classical music, has some original folk tradition behind it. Clever writers and publishers are aware, of course, that copyright law does not cover what is called public domain material, and often delve into the past to find inspiration, even wealth and fame, by taking some old song, and copyrighting their own version. For example, Huddie Ledbetter, a.k.a. "Leadbelly," after his release from prison, had a wealth of material he'd learned working the chain gangs, and many of the songs that bare his name as the song writer are actually public domain in origin. The classic example is "Midnight Special." When Creedence Clearwater Revival recorded this song, they credited Leadbelly as the original writer, which they were required to do under law because they recorded his version. There are many more verses of this song that Leadbelly's handlers did not copyright, and John Fogerty and company could have saved themselves a few bucks copyrighting a different version, had they even been aware of this possibility. The number of old folk melodies that Bob Dylan wrote new lyrics to is, of course, legion, and legendary. 'Nuff said. If you need a good source for origins, look up the works of Alan Lomax and son, in the music section of a good library, and check out Woody Guthrie, too, who covered most of the bases in the field of traditional American music.