Very cute and the simplicity is great. But oh boy it is hard. I ended up not going past the swapping blocks. Sorry, but I feel it is kinda unfairly hard haha, not feeling like trying to beat it.
Also, the way the mermaid charms you feels bad when you get charmed on the top of your jump or mid-jump. I think this is mostly because it is hard to internalize the range of the effect. Maybe adding something visual to the range would help.
But overall, very cute, solid and concise game. Congratulations!