>> child ballad number61,has only one version <<

MtheGM has already given a good answer to that point, but it's also worth mentioning that Child included a lot of stuff that probably never had much purchase on the public imagination or the oral tradition (and of course he missed out a few good uns as well). Modern singers, however, are quite happy to take some of those obscurities and work them up into perfectly good, gripping ballads, and long may they continue.

Inclusion in or exclusion from Child's collection is not necessarily a measure of the 'folkness' of any ballad, although your last point about studying the style is a good one.

Oh, and 'process' is an observable phenomenon, not a law.