The idea is great. I can see a interesting game where scaling your size also scale a bunch of other variables

I grabbed many parts, but after taking them back, they didn't do anything?

The level design fit the game very well. Try to space out your tutorial though. Instead of throwing everything at the player at once slowly introduce them to each mechanic one a time while they progress through the level. Great job :)

I believe this was made in Scratch (correct me if I am wrong), which is surprising given how responsive it feels. You have done a great job!