The thing that made autogyros (and helicopter autorotations) click in my mind was when someone pointed out that the outside of the rotors is spinning faster tha

The thing that made autogyros (and helicopter autorotations) click in my mind was when someone pointed out that the outside of the rotors is spinning faster than the inside. As such, there's a balance where some point inward of the rotor tips will be driven by air flowing through causing the outside to spin fast enough to generate positive lift. There's obviously more to it, but if anyone is wondering why air going up through a rotor somehow causes that rotor to push air back down, this might be a helpful way to think of it.