If you believe that our experiences shape us, then you are likely to believe that we can't be everything. We can only be one person. We might change in the course of time, but we can't be two persons at once. Who we are today, just as who we will be in the future, is created by the places we go, the people we meet and the communities we inhabit. It follows that the things we come to believe and value are also shaped by where and how we live.
Since we as a human race do not have a beehive brain, it is difficult to put ourselves in other people's shoes. But anyone who wants to know more than one's limiting, limited existence will want to put on other's shoes, or at least imagine what it would be like to walk in them. This is why we read books, travel and watch movies. We are curious about how others live, we are curious about the world "out there." Implicit in this curiosity is the knowledge that we can't know everything and that we see only from our own partial, parochial viewpoint. Our views are held hostage by our locality - our inability to be everywhere at any time.
As humans we do have a tendency to prefer living in our own skin, and sticking close to kith and kin. Maybe laws of evolution have pre-programmed our brains to want to stay close to our kind - our "in-group." We create all sorts of myths and norms to assure our in-group's continued existence, including illusions of inherent superiority, even invulnerability. In turn the we denigrate, even demonise "out-groups." We find in others faults, things to fear and things to ridicule to highlight the harmony and goodness of our own kind.
So these are two contradicting tendencies we have in us as symbol-making bipeds. To insist on living either extremes is not only stupid and dangerous, but inhuman.