I'm back with another problem that is probably super easily solvable but with which I'm still struggling.
My object (in this case a person's robe) clips through the floor in material preview, which I did on purpose to try and compensate for what happens when I render it: namely, that the robe appears to levitate an inch above the floor. It didn't work, obviously, because even when I do that it's still offset in the render. I have the robe parented to the person it's on. At first I thought it was a midlevel thing on the displacement; they're all at their default .5 though and editing them makes it worse. So I'm stumped... Here's an example of what the robe looks like in both material preview and the render