There's a few issues I have with this.
You shouldn't require mouse controls unless absolutely necessary. Hitting space should be enough to restart the level or take you to the next level.
There's nothing stopping you from just reversing endlessly to fly. Most games like this make it so you have to hit the ground to flip it again.
The hitboxes feel unusually large. I feel like I keep dying just by going vaguely near some spikes.
I feel like some of the levels are layed out with the easy part at the beginning and the hard part at the end. That makes it so you have to do the easier and more tedious part over and over every time you want to try a hard part. It's better to make it start hard and get easier.