Needs work, but otherwise good
Improve you collision detection for the land. I can fall and enter the land from BELOW ground level. Then you can just jump back up to ground level. Try using a premade CD.
Also, you might want to change the attacks to have a larger range (so that it is harder to be damaged while attacking). The damage hit boxes seem to be misplaced, allowing you to take damage when you kill an enemy (same for both yoshis).
The Replay button does not function.
Consider making a level goal along with (or instead of, your choice) the boss enemy goal (queuing next level when enemy is beaten). This would activate upon being walked into and would replace the black dot which must be attacked (therefore I assume it is an enemy, but I might be wrong, in which case, ignore this bit). Example: Flag in super mario.
Make the traps more obvious. Spikes are clearly harmful while glowing puddles could be decoration.
There are probably more problems and glitches, but I didn't get any farther.
Your game has potential. Good Luck!