I've heard there's a German phrase for it. It's the sensation you experience when you realise that every other person in the world has a whole life going on, with their own beautiful/tragic/hilarious/passionate life stories that you have no idea about.
Basically travel reminds me that the world is jam-packed with interesting characters. They're in every pub, walking along every street, living in every house.
These last 12 months I've been visiting places in New Zealand I've never been to. One of the highlights was taking my parents to the Chatham Islands. Now, usually (and probably surprisingly) I'm quite shy. Especially around strangers. Thankfully, my parents are real talkers and got the locals chatting. It was a fascinating insight into life in isolation.
Not only was there a deep reliance on each other, there were also generations-long rivalries. Basically it was all incredibly fascinating and my mind came up with at least a dozen movie ideas.