I left home almost 10 years ago. Realizing that made me more introspective than usual, so if you'll allow me a bit of 'me-me-me,' here it is.
My first and biggest lesson was that I'm not actually that dark-skinned. I lived for a few good years with that illusion, spending way too much time outside in the sun, mostly on the basketball court. Then I went to university and after a few months under the grey English skies I realized my real color is what some would call a Casper White, or simply just translucent.
More seriously, I learned (too slowly) over time how easy it is to lose relationships from a distance, not by design but through inaction. You don't see a friend for months, then you visit home and make plans but something comes up or you're too tired and reschedule; you do this a couple of times and next thing you know it's been a year or two or more and you have one more acquaintance and one fewer friend.
That's because life goes on no matter what little adventures you create for yourself. Being halfway across the globe from family and close friends forces you to grow, and grow quickly. But life back home goes on without you: people form new relationships, people fall ill, people die. And you're forced to handle all of that from a distance or deal with the shock upon return. But the world won't stand still for you, and that can be a tough lesson but an absolutely necessary one because it forces you to reassess your relationships and define exactly what and and who is important to you.
Years ago I would say to myself that traveling and moving around is great because it allows you to meet like-minded people in far away places. Now I believe the real value is that it allows you to meet and connect with people who aren't like-minded, and these relationships are the ones that change your perspective the most.
What I still haven't managed to do is live more for others, be less egotistic and solipsistic, but that's one of the many things I believe is worth striving towards.
And that's that on the 'me me me' front.