Really enjoyable to play. The presentation is top-notch and the game feel is so good. Well done!
As for the things that I'd change: First, I'd make it so that the charged boomerang shot is actually charged by holding a button (RMB or something) instead of simply waiting, which takes the agency from the player (I'd pair this with a bit shorter charge duration). Second, I was not entirely sure if the upgrades I buy in the shop need equipping or if they are all simultaneously active, so I'd make that a bit clearer. Third, I'd make enemies pass through you on impact - having snakes block your path gets kinda annoying. And, last, I'd try to somehow teach the player that the big enemies should be attacked with the charged shot instead of trying to loop a boomerang behind their back.
A long feedback, but I still think your game is great! Keep working on it, please! :)