The first person to get all 6 stars, congrats! Thank you for playing it until the end. The collisions annoy me too...
My intended idea was having the smallest objects have no collision with the player, that way you could run right over them. When you get big it gets really difficult to see the small objects, and unrealistic that they'd stop you.
When I disabled collision layers and masks though, it'd make running into small objects fly all over the place. I really couldn't figure out how to make no-collision happen. This was tricky because the player's nozzle needs to still interact. On top of that I had certain objects like tables and counters that needed to let other objects sit on top, exit, then not return, all while colliding with the player.
On my last attempt to get it all working I nearly broke the whole damn game and decided to leave it and move on.