I walked on to the UNH team several years ago even though my high school PRs weren't that impressive (2:00, 4:41, 10:08, 16:47). I stuck around for 2 years before deciding to quit because I wanted a better overall college experience. Coach Boulanger (Coach B) is a good guy and let me train with the guys during XC before putting me on the roster during indoor track.
He did the same for several other guys, many of whom developed to be much better runners in college than me. One of the guys went from never breaking 17 in a 5k to running 33:30ish in his first 10k later that year. Another guy was a mid-17 HS kid who wasn't making much of an impact in college track, but he loved running and wanted to continue training. Coach B put him on a marathon training plan and he ended up running a 2:50 marathon later that year.
You probably won't run in races with those PRs, but I can almost guarantee if you go up to Coach B and explain that you want to improve, he'll set you up with a training plan. UNH has turned a bunch of good (but not great) HS runners into conference champions or ones with good PRs, so I'm sure the same can be done for you.
My only advice, wherever you go to college, is that running isn't everything. It may be the most important thing in your life in HS, but things will change. Running on any team in college is tough and time-consuming. You can always train on your own and still improve. I met several other students during my JR and SR years at UNH who ran in HS but decided not to join the team. We ran together a few days a week and had a lot of fun without the huge team time committment. Hope this helps.