Its only because this game is so well made that I can give it notes like I am about to, Its a great game! Many things to love about it. SPOILERS AHEAD: so go play the game, it'll be worth your time I swear.
This is a really neat concept and like the other commenters have said I really only had to jump for most levels. I think the first time I felt I needed to use the newtons 3rd law box trick was on about level 8 or so.
Level 9 was quite frustrating, there was two vocal cues one about the spotlight and one about using the thing to move the box and i spent a minute trying to box through and then myself too somehow, the thing I didnt realize was the translucent blobs were not lethal to me (I now assume they are like fizz grids from portal) so i just jumped through and completed the level and its only upon reflecting upon this as I write I realize the idea is to pass the box to yourself to complete the jump that comes after, which is a really neat idea! Shame I didnt get to experience it that way :(
In fact every room it almost becomes easier to simply jump than to engage with the mechanic which is such a shame, room 11 I spent an attempt or four failing to use the fire extinguisher and upon accidentally throwing it into the danger zone I just jumped and wasd'd my way to victory (there's a straight shot to the opposite platform and then to the switch and back)
The last level I couldn't beat, it was abundantly clear that I needed to somehow break the glass but I had no idea how, I tried throwing spiders at it, the box at it, I tried jumping at it , using shift, everything I could think of and nothing worked which is really sad because I wanted to see the ending :(
I will say there was a neat moment wherein I used a box to push the spider out of the way so I could fly by which made me feel very clever.
The voice acting is really good and quite charming although I wish there was music or more sound ambiance when its over, there was one or two times when I took longer on a puzzle and it left a bit of dead air which made me feel lonely/awkward.
The voice acting is lovely, the spiders are very spooky and this is all-together a very polished game I just wished it made me engage with the parts of it that are the most interesting, the physics and problem solving. I also wish it wasnt a download as this game deserves so so many more eyes on it. Keep it up and I can't wait to see what else you guys make!