pete seeger calls it "the folk process" because he's a genius:
"Mbube" (Zulu for "lion") was first recorded by its writer, Solomon Linda, and his group, The Evening Birds, in 1939. Gallo Record Company paid Linda a single fee for the recording and no royalties. "Mbube" became a hit throughout South Africa and sold about 100,000 copies during the 1940s. The song became so popular that Mbube lent its name to a style of African a cappella music, though the style has since been mostly replaced by isicathamiya (a softer version).
Alan Lomax brought the song to the attention of Pete Seeger of the folk group The Weavers. It was on one of several records Lomax loaned to Seeger. After having performed the song for at least a year in their concerts, in November, 1951, they recorded their version entitled "Wimoweh", a mishearing of the original song's chorus of 'uyimbube' (meaning "you're a lion"). Pete Seeger had made some of his own additions to the melody. The song was credited exclusively to Paul Campbell (Campbell being a pseudonym for the four members of the group: Lee Hays, Fred Hellerman, Ronnie Gilbert, and Pete Seeger). Linda's name was unknown at the time, to a point where he did not receive credit even on his own original release of the song, "Mbube". Solomon Linda would not receive actual credit until years later, one of the earliest being Miriam Makeba's 1960 version of "Mbube" (credited to "J. Linda") when she came to the US and performed the song live at Webster Hall in New York City, accompanied by the Chad Mitchell Trio, released on her debut album on RCA Victor. (Note that on many CD releases of early versions, credits were updated to include Linda as the original song's composer, including the Weavers and the Kingston Trio versions.)