This one isn't too hard to figure out. Moll's positions in life range from mistress to wife to whore, and we readers follow her through every twist, turn, and change of fortune. Like all good protagonists, she triumphs in the end, using her wit, resources, and ingenuity to come out on top, with a love interest and property in the New World, to boot.
In many ways, Moll is like an upside-down Cinderella: she starts out in poor conditions and her great beauty allows her to make romantic attachments with apparently quite eligible men. Okay, we realize that sounds exactly like Cinderella. However, after that, everything's backward: the men she gets involved with are all totally inappropriate in one way or another, and she moves from one to the next in a downward trajectory that Cinderella would probably never take part in. This is not a woman who waits around for Prince Charming.