If you view the stories of the Bible logically, the Wife of Cain shouldn’t have existed. At that point in the story, the only humans alive were Cain himself, and his parents, Adam and Eve.
If you skip ahead in the story, you see that Adam and Eve did eventually have other children, and Cain could have married one of his sisters or nieces. (One must assume that that was allowed for a few generations, at least, or that second generation would have been the last.)
Cain’s descendants don’t appear to play a large part in the greater story of humankind, since, according to the genealogies, the only survivors of the flood were Noah and his sons, and Noah (as well as everyone else after the flood) was a descendant of Cain’s later brother, Seth.
(Come to think of it, the Bible only traces the father’s line. We have no idea who Noah’s wife was, and she may well have been of Cain’s line. So we may all be descendants of Cain after all.)
The Bible simply mentions the wife once, as if her existence was not surprising. The story demands that the wife exists, so she exists, perhaps pulled into reality by the needs of what would become history.
In this telling, Cain is tormented by the memory of his crime and punishment, yet is given a chance for repentance — not merely by saying that he is sorry, but by learning to raise his son and to deal with his inevitable anger in more effective ways.
This is the first mention or appearance of Asherah. Later, she becomes a goddess figure, worshipped both independently and as a bride of God by future generations. Perhaps this figure is the goddess herself. Perhaps the ancestral memory of her grows into the story of the Goddess. Perhaps the stories needed her again, so again she appeared, in whatever guise the world needed her.
Have you seen stories reach back and become memory? What parts of your history, or the history of your family or community, may not have happened the way that they are remembered, but, by force of a story being told again and again, have become effectively true?