I really like your idea of having to switch between two characters and each serving a purpose that requires you to use both. Sadly though I wasn't able to get fairly far and I couldn't grab the key I needed to progress further. As others mentioned the first level should be there to help teach the player how to play the game with having little consequences. I'd recommend that you look at how other games like Super Mario Bros. and Super Mario 64 on how they approach designing the opening levels to their game. Overall though great job getting this done in time for the jam!