I read one of Ong's books long ago and have entirely forgotten it. Might give it another go. But as some of us have been pointing out, the relationship between oral and written traditions is more complicated than you seem to be suggesting. All the songs in Child were created in a literate culture, most of them probably entered the tradition on paper, and paper versions of them have been part of the chain of transmission everywhere. Someone creating a broadside for sale, or making a copy in a commonplace book, is just as likely to introduce changes as somebody reproducing a song from memory, and the changes they introduce are likely to be more drastic. And many of the stories in British folksong have been preserved in writing from millennia before the English language existed - anybody writing a song about a frog courting a mouse could read Aesop.

I would run a mile from anybody proposing to talk about Jung in this context. There are theories of how stories work that employ archetypes of some sort - Child uses them in his classification scheme, Propp developed the idea extensively, they are a commonplace in structuralism - but they don't require the bizarre mixtures of New Age religion and Theosophical racism that Jung was committed to, or his grandiloquent pseudo-messianic pretentiousness.