Does the game end at the end-level door? I got that far but couldn't enter it.
This is a weird demake. In a way - I'm not sure it's necessary, as NES graphics look only marginally different than the game's original EGA. Furthermore, I'm afraid you lost a large part of the original Dangerous Dave's appeal when you made player and enemy sprites chibi.
While it doesn't really work as a demake - it might still work as an original game. Add more enemies/obstacles, spruce up the level design, and maybe give the player more abilities - and bam! Original game: )