Although many have complained about the controls, I thought having to click to move on a grid created an interesting and unique challenge. Admittedly there's a reason most people don't go for this design, but I didn't think it was out of place in this game.
However, I think this is a great first jam submission! You did a good job fleshing out the game with the waves and upgrades. If you make any of this type of game in the future, you may want to look into increasing the wave intensity logarithmically as it will get the player to more difficult waves at a decent rate but then doesn't drown them in later levels.
I may have encountered a but where I tried to heal but my health didn't seem to go up, or maybe it just wasn't updated.
Overall, great job, hope you can compete in the next jam!