I agree, the mouse is a bit awkward but the idea was to have those buttons not be awkward or interrupt the left hand when moving with WASD. It's something we would have worked through with more time, but that's a game jam for you!
True, If that can help a layout i like is arrow Key and Z,X,C,Shift, space. Lot of game use that. I also have see stuff like WASD to move with JKL for other stuff like map or dodge, it's rare but i found it great too .... For plateformer i personnaly don't like using mouse (exept if the game is intend to be played with it like for aiming). You can play with 2 hands on keyboard, it's not limited to WASD and around, you just need to do a tutorial for the controls (not like my game this jam XD)