I used to do A LOT of 5k's (3.1 miles). I would break 20 minutes, usually. If I was under a certain weight. That's about a 6:22 mile/average.
Right now, I can do ONE mile EASILY in 6:00. But, that is ONE mile. There is a HUGE difference in ONE mile vs. two mile, three miles, etc....
I ran 5 miles today in 36 minutes. That's about 7:12/mile. I'm getting older (35 in two weeks), but my pace is similar to what it was in my late 20's when I was doing 5k's competitively. I did few marathons in my early 30's and hope to do a few more. The 5k's are still fun, but it's not what I train for anymore. I train mostly to burn calories now. So, 5k's are not as good for me for "burning calories" (simply because I like to run longer than 20 minutes).
But, to the topic of this thread. I think A LOT more people can run a 6:30 mile if that is it. ONE mile is pretty easy. It's really a sprint if you think about it.
I've never broken 5 minutes. I came close. I did a 5:03 once. I am about 180 right now. I was about 158-160 back then. If I get under 175 now, my speed really picks up. I think this is the same for most people, regular runners or not.