Thank you for pointing these things out, that bottomless pit was reported by a number of players and I've taken steps to rewrite how pits kill the player. Hopefully this prevents any more endless death pits. I've also taken your critique of the color contrast and completely changed the palette of the background. Hopefully it looks even better once I add scrolling and parallax.
I've also added d-pad functionality and I agree it definitely feels right for a precision platformer. Thank you for taking the time to help me.