Just got fired as a cashier (20M) what do I do?

I got a job at a bookstore and the only available position was being a cashier. I had a feeling I’d suck in that position but I needed money so I went with it. I worked for about two weeks and was told I wasn’t competent enough to continue working further. I am in college currently and have been trying to find a stable job to work part time while in school but at this point I might as well wait until I graduate.

I keep hearing about how much the job market sucks so a part of me is a little hopeless but maybe working a full time adult job would be better.