Great job finishing a game for the jam. It definitely fits the theme well! I like the idea a lot, having these random containers and trying to jam as many tetronimoes in as you can. There are lots of ways you could make a very compelling game out of that mechanic and it sounds like you would have liked to work on that if you had time. Very relatable!
As a jam-specific pointer, it can pay off to give players more of a "complete experience" of playing the game, even if what you make isn't in-line with what you wanted. For instance, you could have made the timer shorter each time the player solved one down to a minimum value, and then give the player a "victory" screen after they complete a certain number of shipments. That way, jammers aren't left playing an infinite game wondering "is there more to see or am I finished?"
Anyway, congrats on making the game! Super impressive, hopefully see you next LD!