Perhaps twin sticks then if you don't wanna use a mouse? Left stick to move, right to aim, wasd to move and arrow keys to aim? Something more accessible for the fire button like space or the trigger on a controller if you went with what i suggested? Or even shoot when you aim kinda like in Binding of Isaac if you've ever played that.
If you change them after tha jam then do let me know if you remember :) Would like to try again