I am still 18 and started college, and I want to be a back-end developer. I have a fairly decent knowledge of programming and have been programming for ~8 years, but I've never really put in the effort of finishing anything. Would it be smart to finish several different projects to put on a resume? Would recruiters be interested in actually looking at those projects? Thanks.
Recruiters are not very likely to be interested in any projects that you have done, though it may be worth it to mention it if they are seeking you out for a specific role in mind. For example, if the role they are trying to fill is a database admin role, you may want to mention a project where you stood up a database and managed it.
As a hiring manager, I always look for GitHub or similar repositories. If you're not on GitHub already, I would encourage you to create an account and upload your code. This shows me where you are on your coding journey as well as you knowing how to use git.