Not bad for a first game, honestly. I'd say the centipedes movement AI is actually really impressive for a first timer, they're natural and smooth as hell not gonna lie. Music is good too, if you did that as well then great job there.
As expected this is super simple for me to have much things to say about it, but that's understandable, hope you keep up with game deving on the future too.

The main critique I can give is that next time you should make a better indication of when I can or can't shoot, like making some visual change on the player sprite or something like that, It's not really intuitive to have to look all the way up to the top of the screen to know about that, and I can't keep spamming either since if I do I'll destroy more mushrooms and block myself again.