Explanation: While Virgil's Aeneid is pretty well known, only fragmentary records remain of his two main influences: Ennius' Annales and, most importantly, Naevius' Bellum Poenicum, the first Latin epic poem (that we know of).
Of the Annales, written in the 2nd century BC, we have 600-ish fragmentary lines, and it was one of the biggest Latin epic poems of its time, recounting Rome's history from the Trojan War to the Aetolian War. It fell out of grace sometime after the Imperial Age, with Virgil already criticizing Ennius' "crude style".
But far more fascinating is the Bellum Poenicum, written during the 3rd century BC: almost completely lost to time (we only have 50-ish fragments, most of which one-liners), we know very little about it. Written in "Saturnian", the old Latin/Italic poetic form indigenous to Italy (perhaps inspired by Greek poetry, but it's difficult to say), it wove history and myth together, perhaps even including Aeneas and Dido's love story. If this was true, it would paint a much stronger connection between the Bellum Poenicum and Virgil's literary masterpiece.
Although difficult to ascertain, the meme is exaggerated and Naevius was (probably) NOT the "creator" of Aeneas' myth. It could have been much older than that, although our knowledge of the humble beginnings of Rome's literature is so spotty, that even making wild guesses would somehow feel wrong.
(EDITed with a bit more clarifications)