I'm into games like this. I play a lot of Skate Boardin' for the Atari 2600 to this day trying to get a better time finding all the pipes and stairwells to grind. This has a lot of the same elements that I find fun in that game.

One thing that might be cool is a timer, where you have maybe 2 minutes to pick everything up. Cars wouldn't kill you or end the game, but you'd lose 5 seconds getting back on your bike, and you see how many pieces of trash you can collect in the time limit.

Editing to add: I looooove your bike rider sprites, they are really cute and look great!

Thank you so much for your comment! It's a school project we did in 2 weeks so there is a lot to improve and we will remmeber your advice!