... all people spoke the same language?

The first thought you might have is that life and especially communication would be a lot easier. There wouldn't be a language barrier holding us back while getting to know people from all around the world.

Speaking the same language might be helpful in order to connect with people in private but also on a professional level, for example agreeing on business deals, because the risk of misunderstanding each other is not as high. The education systems all around the world would also benefit from monolingualism. The same school books could be used at every school by everyone no matter where you are from. This would ensure that every child gets the same level of education even if it moves to a new country. Furthermore, there would not be any use of translators anymore.
All in all, communication would be a lot easier and effortless. However, the power and beauty of having different languages would be gone. Power of expressing feelings and cultural exchange would be reduced to only one language. Language is a big part of culture and by speaking only one language we would assimilate different cultures into one melting pot. There would be less cultural diversity. By losing such a big part of the culture of a country we would also lose the admiration for a foreign country and culture because it would not seem so foreign anymore. We would become lazier because there would not be any need for learning a new language and really deal with a new culture and its identity because it would feel so familiar.
Furthermore, a language is also always connected with history. That means we would disconnect from the history of the language because it would not be passed on from generation to generation.
In addition, the excitement of getting to know a new country including its language would fade away as there would be fewer differences and more similarities.
If we were limited to only one language we would simultaneously reduce ways of expressing what we feel and think. There would be less creativeness because all literature and all music would sound the same. Therefore, we would lose traditional music and literature which would make the earth a much more boring place.
The thought of speaking only one language all around the world would also lead to the question what kind of language it would it be. Would we make up a completely new language or choose a language that already exists? And what would happen with the different dialects of a language ?
What do you think about this topic? Would you prefer everyone speaking the same language or do you like the language diversity?