@Sect Patriact I think it's not big shot ghosts but actual deities. Most Korean theology and mythology embrace the concept of multiple gods that represent different aspect of life or concepts that they understood. I'm willing to bet that seonangshin was actually fighting actual ghosts which in this case "gwishin"—would you look at that the title "gwi" meaning ghost and "chon" for village, literally saying "ghost village."—the gwishin seeing how outclassed it was with the divine tree present resorted to pretending to be Sungmo the "holy mother," and giving the village chief false revelations about the tree.
Another Theory of mine is that the "Mother" is another diety that is pretending to be Sungmo, I got this from the comment about the tree being a bodhisattva. Someone that fits the bill would be Xiwangmu a Chinese diety that has mŭ (mother) in her name, and although now she's seen in a benevolent light now; some text did say she was a wild demonic diety once.
Don't qoute me on this if I'm wrong because most of these are secondhand info I got from a friend whose hobby include studying Asian mythos.
Take everything with a grain of salt
