People live on the island year round. It's true. They look like everyone else. For all you know they could be standing right next to you! Da-da-daaa!
Okay, but actually there is a Mackinac Island community behind the scenes. One of the best examples for this is the tiny, adorable school. You can find it by riding into town and head toward the library. Keep going until you find the sign and playground. Kids do live on the island. Really, it's just like any other town. They buy their groceries at Doud's, go to church at one of the churches, and hang at the 'stang. (Fun fact alert; that is what they call going to the Mustang Bar. They literally call it hanging at the 'stang. That is awesome.)
The children of Mackinac Island put together a little booklet of frequently asked questions. We have a couple copies at the House to show to guests. It is adorable.
I also highly recommend that you check out the Mackinac Island Public Library. It's the cutest blue building at the very end of town and decorated with local artists.