100–200 years is not that long in the grand scheme of things. So, the world has only recently become “globalized.”
Before countries around the world started to trade freely, before the industrialization period, it was only normal to produce for yourself and your family, from food to clothing. And this meant just minding your own business, having relations with people in your community/town, and speaking your mother tongue for the majority.
That is not the world we’re living in right now. You meet foreigners or you meet people who’ve been to other places, at least. Therefore, our relationship with humanity cannot be the same as before.
Everyone cannot hold the same exact views because they are shaped by experiences. Our role as decent human beings is to know people are not (and should not be) copies of each other, they have different opinions. If not murdering someone from your tribe was the custom centuries ago, our standards need to rise now. We need to be willing to hear each other. That’s the first step towards appreciating the differences instead of resenting them.