Market dynamics do a pretty good job of translating how a civilization's uniqueness produces an output that gets placed into relative valuation against the output of everyone else. Then, military power affects control over the rewards of trade. Everything else is just details.
We're not in a post-scarcity world yet, so history even up until now is tinged with colonialist flavors. Even diverse, unique, different colonized peoples engaged in exploitation and violence against others to one degree or another, so it's a strange moral position IMO. I think the element of Western chauvinism to be avoided is the rationalization of power as a product of deserving cultural traits. Ironically, post-colonial globalism is continuing this Western tradition, just through superficial self-hatred.
I like the idea that distant lands will be post-plague or post-invasion crisis and start the age with a large disadvantage. This makes the player and its neighbors the "winners" by luck of history, but that is how it goes...
I'm making an England mod right now, and their remarkable 17th century is infused with notions of destiny and culturally merited success. The Spanish also had similar ideas. It's not so much that we're validating these beliefs as universal, but recognizing that this is how these cultures believed at the time and it is part of their objective "success" in expanding and asserting political control and exerting cultural influence. We want to play these games like we're removed from what these civilizations were, like we don't belief in Amun-Ra or sacrifice to Tanit. But we are in fact part of some civilization or another, and the reason we possess a Western bias to a degree is because the West "won" the IRL game. It's hard to disentangle because this doesn't make the West superior, it just means that the West won, and so obviously the West will believe the West is superior or have that as part of its culture. We don't have a game where someone else besides the West won, but that would certainly be interesting.
It would be a legitimately indeterminant debate if two factions of sociologists debated whether some other version of "victory" after the exploration age could have created today's world, other than the expansionist, economic one obtained by the West. Some would be material determinists and insist that whoever had won history, had to become colonial. Others might argue there might have been other ways for the world to globalize. It's hard to make a game about things we don't know.
In my solution for the game, the distant lands will be weak and antiquity tiered. But you could be the mighty scientific Shawnee sailing up the benighted Thames River to trade with the poor, depopulated English. So the forms of Western bias remain, but the cultural identities embodying them don't have to be Western.
