Hello! Welcome to Feedback Quest 5!
Playing through, I immediately felt like I had a better idea of what I was doing and what was going on compared to last time. I went through a few of the levels, having fun with my jumping and shooting while noting things that I felt should be covered.
One thing that was brought up already was the loss of keys upon death after a checkpoint. While collectibles stay, keys are lost and the player is forced to restart from the hub (not even just the level) to go back and get them.
Another thing was crumbling blocks vanishing from just touching them but not walking on them. While they do respawn, this can lead to some confusion from players and they may not realize until later that they respawn.
I had a point in one stage where I tried to kill myself on a spiked wall and ended up in the wall. That was fun. XD
Finally, one particular behaviour that I dislike from this, even though some of the games that are inspiring you did this, was that flying enemies could pass through walls if attacking you. I personally think they should be forced to fly around, both for consistency and to make a better challenge to the player. When enemies just beeline for you, you can usually move back and eventually get an easy shot on them.
I can't wait to see more! :D