Impressive for a first game! I liked the gameplay loop, having to keep the screen "clean" is a good way to keep up the pace of the gameplay. The sprite's "fullness" conveying health was a nice touch, although for several runs I didn't know that was the case and just thought I was dying randomly.
The upgrades could be a bit more frequent, having to play for minutes before the first upgrade dampens the impact significantly. The challenge felt fair, and consistent. Honestly, quite a fun experience! And that cover art - Possibly best in the jam.