This game is really, really cute! <3 The story fits very well with the theme too!
About the graphics:
I very much like the indie-game aesthetics - especially the cute little animation of the character when walking, sliding and jumping/falling! Also the parallax effect with the graphics in the background is adding a lot of charme to it!
The biggest issue of this game - in my opinion - is that the resolution of the overlays got changed somehow (that might have happened when you were porting it to WebGL, or you didnt set the canvas that it was on to scale automatically with screen size). By that I mean the resolution of the newspaper-menu, and also the green effect of (what I assume to be) the radioactive poisoning. That somewhat hurts the immersion, and also makes the lines in the newspaper hard to read!
The background picture in the main menu also seems a little warped, like it was forced into a different aspect ration. That's just a minor nitpick though!
The reflections on the water seemed to be a little inconsistent. In the first level, I could see myself being reflected in the water, but later in later levels I could not see myself there anymore. In general I would suggest making the reflections smaller too, because they can be somewhat distracting.
About the gameplay
The actions of walking and jumping are simple and very intuitive for a platformer! But the sliding actually took me a bit to figure out - it seems a little inconsistent and is also not explained anywhere. It would be cool to have a very simple explanation of the character movement in the start menu.
I feel like the jumps could be adjusted to be just a liiiiittle bit higher, because some jumps from one lower platform on an elevated one (which I assume are supposed to be makable) often require a lot of tries to get them, and the higher platform seems to be just barely out of reach because of that. Some of the jumps really required a lot of precision, but that is okay because the character can be controlled mid-air.
Two other things that I noticed in my playthrough: The radioactive poisoning really catches you by surprise, and it's not explained where it's coming from / which zones actually poison you and which are not (I figured it's the "outside" zones, when you dont have a roof over your head anymore). Also pushing a button feels like an impact is missing, because if you dont see anything move, then you dont know that the button did something at all. My suggestion would be to add a button-pressing sound effect or animation, just so that the player gets a little bit of feedback, that the button was actually pressed!
Sloped surfaces also seemed to be a litle janky, because you can run up slopes while you are on them, but if you are on even ground, you can not run up a slope anymore.
One last thing - though not exactly gameplay related - but I very much liked the backrgound music, and especially the fact that you had a volume slider to adjust it!! :)
That's all the feedback I got, I hope it helps you! You definitely have put together a really cute game, and I enjoyed playing it! <3