Just because all people know the same language doesn't mean we all will suddenly change our personalities and want the same things and discard all traditions and values and change everything about us and our countries. There are people who speak the same language as you and think everything about you and your beliefs is wrong.

Language changes all the time and is combination of countless other different languages, it's just a tool for communication. We created all these languages, it's not clear to me why we can't change them to make life easier for everyone, preserve them sure, preserve books and have educated people around who still know these languages.

Only reason you speak the language you do is because someone long time ago decided that place where you were born will use that language, there was no real reason behind it, it's just what happened, probably because they spoke that language. More to that even the language you speak now just couple of hundred years ago would be gibberish to you, language changes, you can't stop it. There are dozens of new words being created every year, words that weren't part of language suddenly are in use and then all you can do is declare that they are now officially part of that language and move on.

Chaining language to all these different countries is nothing but people holding on to the past for no actual reason, we can do whatever we want, there is no limit to what you can choose to do.