What is the tittles for these positions?

1, Some people work in a warehouse, and their jobs is to get ready the stuffs from the invoices, then the drivers can deliver the stuffs to the customers. So, these people are called stuffmen? or??
2, what is the business of selling every part of cars called? Auto part company? or?
I am trying to learn how to write a resume for myself. So please spear your time on doing me a little favor. Ts.

warehouse worker, period. NO job in the US is called STUFF anything!

parts salesman

you will not need any resume to work as a beginning clerk anywhere.