protomyth means an initial form of a myth that is inferred or known about only from secondary sources; a motif that is not yet accorded the status of myth, but may (it is supposed) become one. Lexicurio rates it Sui generis — a strength score of 87 out of 100.
Why “protomyth” is a great word
PROTOMYTH — [Noun] An initial or inferred form of a myth, known only from secondary sources, or a motif not yet accorded full mythic status. From the combining form proto- ("first, original") + myth ("a traditional story"). Unlike an ur-myth (which denotes a fundamental, archetypal, or hypothesized original from which others derive) or an origin myth (which is a culturally recognized story explaining beginnings), a protomyth is a scholarly construct, a preliminary sketch for a legend. It is the faint outline of a hero in a fragmentary epitaph, the charcoal sketch beneath the fresco, or the anomalous symbol on a single shard of pottery—a hypothesis waiting for a story to inhabit it, haunting the edges of our understanding.
Etymology
From proto- + myth.
noun
- An initial form of a myth that is inferred or known about only from secondary sources; a motif that is not yet accorded the status of myth, but may (it is supposed) become one.“In the protomyth, for which the Latvian and Indie myths give evidence, the sun-maiden, which Helen strongly resembles, was married to the divine horsemen (v. (Robbins) Dexter [1980]: 21-22; Dexter [1984]: 138-142).”