Sorry for the late response, I wanted to make sure to test your game before answering.
Yes I am actually surprised of how similar our games are in terms of ideas! I am definitely gonna write a comment under your game as soon as possible.
Reguarding the gameplay loop, I agree it is a bit too fast at the start, in fact in the most updated build (you can find it on my account) I made it slower in the early part of the game and made it a little bit easier in the late game too, I am currently working on a build not published yet in which I am trying to release a more balanced gameplay and a playable tutorial aswell! I am glad you enjoyed the rats mechanic it actually was a last minute suggestion made by a friend that was watching me working on the game hahah.
I am thinking about adding the crates and the trucks slowly, I thought about starting the game with just 2 trucks and slowly adding up to 4 trucks in total, but I am still working on the gameplay design.
I agree that the rats mechanic is a little bit out of place in the gameplay flow, so I am trying to think about how to rework them to make them fit more.
Thank you very much I appreciate the deep analysis, have a good day <3