Very consistent game, consistent graphics, consistent audio. I like the single screen scope of it.
After a bunch of levels the level variety started to feel a bit repetitive where only the amount of enemies would change a bit. (Not sure if in later levels there would be more variety but I only got to the annoying shooting wasps/bees)
Just a small game design idea; it could be cool to not start with all the characters, then you can unlock some characters in some levels and you are forced to go out of your way a bit, for example you could make a character locked behind a bunch of stones you first have to dig through. Then you can gradually learn all the characters and their attacks. And that will make it feel more painful to lose them.
I think something is going wrong in your leaderboard code at start up, it does not show the scores on the main menu but when I check the network tab I see the request successful. Everything seemed to work when I went gameover so I guess that is the most important part.
I managed to get to the top of the leaderboard for now but I'm sure someone else will beat me as I did not even make it through all the levels. I had fun playing your game. 🌟 (Please let me know when someone overtakes me so I can retry 😅)