Would it be beneficial for the world to stop having a single language and officially create a few different varieties of speak?

I have in the past heard it said that speaking multiple languages is "bad" for your brain. From a purely objective perspective, it seems like there doesn't have to be a single global "standard" language for communication. English is the language I speak in, but I have heard Chinese speakers (or Chinese language speakers in any case), Spanish, Russian (or Russian language speakers), Arabic, and a multitude of others. Having a single language could be a great unifier, but could it be beneficial to have multiple languages? A couple of varieties or so. What would be a reasonable amount of languages and how would these languages get established? If they were to get established, how would language learning change?<br><br>Can we look at two established languages for example and then try to fork them a little bit by adding a special character or a prefix to each word to make it noticeable? Maybe we could change all the vowels completely depending on the language, or change the general syntax completely. Why would this be advantageous? Or would it simply be a burden that humanity and the world doesn't need?<br><br>And if we do have a change in language, would it not be even more difficult for people to learn different languages? Maybe we should start teaching people different languages from a young age, even if it's just the one language that is most foreign (for Americans, that would likely be Mandarin, for Chinese speakers that would likely be English). Would we even see an increase in people speaking multiple languages? What about the vast number of already established languages. What would happen to them? Would this change only be in future generations? Or would it be a mass effort to change the global language<br><br>There's just so many things to consider, I don't know that we have ever done something like this before. I would very much like to hear your thoughts on this topic, if you have any.