lmk if there's something else you need, or if you were wondering about something else instead of this also, since you're new to animation, as far as you've said, I would recommend splitting your head, body, legs(and other parts of sans that you'd animate) into seperate sprites instead of clones of the same sprite, so it's easier to traverse them.
scratch that, they unshared it, so @megalobone for sprites music by benyi