A person who drives vehicles is a "driver"
A person who swims in the water is a "swimmer"
What do you call a person who goes around and picks things up? "pickuper"?
It would be someone who literally grabs a box on the ground and puts it somewhere else (at higher altitude) ie: from the ground to a truck or from the ground to a shelve
An example:
A: I need to pick up these boxes
B: The pickuper will do it for you