The movement feels too quick to be properly controlled. It's very easy to overshoot.
I feel like I want to be able to remove blocks I placed.
Being a pixelart enthusiast, it frustrates me that clicking doesn't create aligned 'pixel' blocks.
Holding jump shouldn't trigger another jump after coming down imo.

At the start of the second level I died immediately with NO idea what I did. Feels frustrating.
Include arrow key and wasd controls please.
The second level feels like a completely different game, if you teach a mechanic in level one, and it doesn't work in level 2 something is wrong.
I couldn't beat level 2 as I have no idea what to do.

Your web link doesn't work, and judging a puzzle game by a video doesn't work very well.
if you want proper feedback make sure it's available for play.

The game looks interesting overall, the end-of-level slime animation is very well done and it makes the rest of the game look very lacking because of the contrast.

The game doesn't seem to work anymore.

The game's graphics don't seem to fit together.
The far-out background is pixelated, the foreground objects are vector-ish and the UI is minimal.

I was surprised by the aim of the enemies, the way they lead. It feels a bit unfair though, I feel like I need a dash to escape.

The text should be sharp, try using textmeshpro.
Maybe consider some clouds background for the sky, and gradientish ground fade.
Overall the pixelart feels too small.

The mechanics feel pretty good, but I think the jump could use a tiny bit of tweaking to REALLY make it great.