IMHO, different world travellers come up with different life lessons. It all depends on the person's own prejudices. Lessons are not in the world, they're within you. World and societies are just tools to discover our own selves.
I can't really think of any written example of any traveler who came up with different conclusions about the world.
Conclusions about the world can be same. Like, everyone wants the same in life is a popular conclusion seen in several travel blogs. But we're talking about life lessons here, which I think, are not absolutes but drawn differently by different people.