Personally I don't think you can draw much in the way of conclusions based on 2 interviews. However, as you mentioned, job interviewing is a skill that can be learned. So if you find you're continuing to not receive anything in the way of job offers, perhaps looking into the possibility of attending a job seeking skills training program might be a worthwhile endeavor?

There is a publishing company that publishes job seeking skills training material. Perhaps some of their publications might be of use as well:

Job Search - Career Development - Browse Products | Paradigm Education Solutions Store

I understand how you feel about minimum wage retail jobs. But everyone has to start somewhere. (Sorry for the platitude.) And if you've never had a job & you're in college perhaps a job in retail isn't such a bad place to start? If your college has a student placement office, perhaps talking your situation over with them might be helpful. Best wishes for success with your job search.