Thanks for all the responses! VERY helpful. So the job you take in the summer after 1L, could that eventually end up leading you to your job after graduation? Or is that more the job you have in the summer at 2L? Do a lot of people use their 1L summer to get a job for their 2L summer, or do people generally do something different?
Some 1L summer jobs lead to further employment, but that's not going to be a strong possibility for the huge majority of the 1L summer jobs that people have. Your 2L summer job has much more of a chance to land you something post-graduation. A lot of people use their 1L summers to explore a field of law they find interesting, to get some hands-on experience with the law, to build contacts, to be able to put down a legal job on their resume, to show interest in a given field to future employers (e.g. if you want to do public interest, but have no pre-LS public interest experience, 1L summer might be a good time to pick that up), to get some good "legal stories" that you can tell during OCI, etc., etc., etc.
Generally, don't sweat 1L summer too much. If you're proactive, you should be able to find some really interesting legal work that serves you well later on; but really, it's not going to make or break you (unless maybe you spend the entire summer doing nothing even remotely law-related, which would throw some red flags up). Every single 2L or 3L I talked to about 1L summer told me that they've never heard of somebody just not being able to find some kind of legal work.