Culture chauvinism and othering

I often wonder which level of education is necessary to understand that the own standards one is used to aren't more right or more justified or “naturally correct” compared to any others.

I know, by nature, that state of mind comes automatically, to believe, only oneself speaks a proper language while all the others are gibberish. Many names for foreign languages came from that understanding, e.g. German, as seen from a Slavic perspective, is called “Nemetski”, referring to them as “those who have no language”, and ancient Greeks called all non-Greeks barbarians which could either refer to them as barbed=uncivilized or as people who only know how to speak “brr brr”.

But even with political ideas and religion you find many who consider their own values as true and right and all the others as lies. From one's own perspective everybody considers themselves as freedom fighter, while from others’ perspective one is simply a terrorist.

So how can we learn to get over with that chauvinism in belief, culture, language, values? How can we learn to stop our constant othering?