I suspect this is yet another instance where, though it may not be a faithful adaptation, it would have paid to have read them anyways. This is what saved the Dune adaptation for me, not needing all of that exposition. I gather that a major part of the premise is that people get reincarnated on schedule, and that one of the young people in the village is some kind of Ersatz Jabberwock whose time has come around and who represents trouble of some kind, which makes them a McGuffin, but the witch isn't sure which one so has to round up everyone within an age spread.