While you don't want to lie or exaggerate your experience, you don't want to shortchange your experience, either. Remember that a resume is a reflection of your experience. This can include volunteer, student organizations, even short-term projects that you might have worked on. Your goal in listing your experience is not to win brownie points for listing the most jobs. Your goal is to highlight the most relevant experience for the position along with a few details.
Remember also that you can highlight your experience in a lot of ways. If you have a lot of jobs or positions in a certain industry, you may want to list them all to demonstrate that. If you only have a few jobs or positions (or doing a career change), use the extra space to detail even more about the position or jobs that you had. Did you get involved in any school projects, organizations, or events? What consistent or special thing were you known for at the job(s) you worked at?
Shifting your perspective on your job experience will also help in the interviewing process. If you only focus on what you don't have, you won't have anything to say, when it's time for the interview. You don't want to do that! Even if you only had one job, there are plenty of skills that you developed Most of that experience can be added to your resume, cover letter, and other job materials to help craft your job story.