Hey! Cute game. I love the commitment to making a game about a topic like this. Good message. The gameplay is fun and simple, and enjoyable, but I have some feedback:
You might want to put icons of the cans on the recycling box, so color-blind folks can play the game easily as well. You might want to indicate which item the crab has collected, so that if they collected something without looking, they can bring it to the correct bin without guessing
You might want to give the player at last 2 lives, since it's a bit frustrating to play for a long time but die because you made one tiny accident.
You might consider a high score tally, for this type of game, to influence the player to replay it.
Forcing the player to re-read the story and controls each time they retry will make players less likely to replay your game.
I like your game and I like the way it portrays the depressing reality of modern life in plastic.