I think that the "arrangements" of traditional songs for which people might claim credit vary widely in just how original they might be.

Most of them, in my opinion, do not and cannot alter a traditional song sufficiently to constitute an original-enough piece of work to merit royalty payments. But there are a couple of exceptions that I'd like to mention.

I Know You Rider: There's an old Mudcat thread, recently brought back to light, discussing this traditional song, which the great Bob Coltman learned from an old Alan Lomax field recording. I'll admit that I have never done the research to find and listen to the original recording, which featured a young woman singer (perhaps a young woman prisoner ~?~), but from what I've read, I have the impression that she probably sang unaccompanied, or perhaps with minimal and unremarkable backing. Bob came up with a quite striking chord progression, very unusual for a song built upon a standard 12-bar-blues structure (and therefore, presumably, original).

Bob never recorded the song, but played it regularly and widely within the then-very-small US folk community, and the artists who first did record the song with its new arrangement were definitely members of those early audiences of his.

Bob ~ a Mudcatter, by the way, and a character with extremely longstanding credentials dating back to the very earliest days of the US folk revival ~ created a song that gradually became a favorite among guitar-playing "folkies" and, eventually, folk-rockers (most notably, Jerry Garcia and the Grateful Dead), as well as their successors, contemporary "jam-band" players.

I feel quite sure that this popularity and longevity is undoubtedly due to the striking chord progression that Bob came up with ~ without that quirky chordal accompaniment, both the melody and the lyrics are pretty ordinary, essentially interchangeable with any other bit of basic 12-bar blues.

House of the Rising Sun: I'm sure that some of you, but not all of you, are familiar with the story of how Dave Van Ronk came up with his very original arrangement ~ again, an unconventional and extremely striking chord progression ~ for a fairly well-known old folk ballad previously sung unaccompanied or performed with a basic and unremarkable three-chord (or even two-chord) background.

Dave was "breaking in" the piece by playing it nightly at various Greenwich Village venues when a young Bob Dylan, at the time just starting to record his first album, asked if he could record Dave's arrangement of the song. Dave said no, he intended to record it himself soon ~ but then learned that Bob had already done it. The song does indeed appear on Bob's eponymous first LP ~ with no credit to Dave and no royalties for him, by the way.

The upshot was that Dave had to drop the song from his repertoire when audiences consistently remarked upon his playing "that Bob Dylan song."

A whopping dose of karmic payback occurred a few years later, when Eric Burdon and the Animals recorded the song, once again with the same chord progression, and "House of the Rising Sun" ceased to be perceived as a Bob Dylan song ~ the masses now heard it as that well-known Animals song, and Bob had to drop it just as his mentor Dave had done years earlier.

Sadly enough, the Van Ronk estate has never collected a penny for Dave's best-known and most commerically successful creation.