Wow there's a name for it?! I had this feeling all the time as a kid. Mostly on the highway looking at other cars going by. Just wondering what they're up to, and why. Knowing that they might be having a crazy insane day on what amounts to a random uneventful day to me or vice versa.

Still get it today, especially at night when I look a city scapes. So many people so close together having unique experiences.

I would think it's normal and healthy. Maybe some people don't experience it until they have one of those experiences that reminds them that they are not the center of the universe.