To say that a language is merely a means of communication is like saying that paint is only needed for painting fences and walls.

Why does it matter that the little Italian restaurant run by the grandmother and her family has closed? We can just all just go to Olive Garden?

Additional to the comments you got - different languages are able to express different things. There's the classic example of Innuits having hundreds of synonyms for snow: I bet you can have a much more nuanced conversation about snow in that language than any other.

Have you ever heard the phrase "lost in translation" and thought about what it actually means?

It's more a matter of "different languages force you to express different things". E.g. English forces you to specify subject and tense, while Chinese makes specifying such things optional.

It's not just that. Some languages are richer than others in various dimensions. For example: English has a single "diminutive"-type suffix but Russian has a vast range to express various related suffixes that allow you to color nouns in a way I can't really convey in English.

This makes Russian more naturally suitable to (for example) poetry, but english for Technical writing

Languages are inseperable from the culture they evolve in. Humour, historical references, values, even entire philosophical concepts can be impossible to adequately translate, because they are often so closely tied to the way a culture’s language developed and is used. Because of that, you‘ll never truly know a culture until you know its language.

(See also: https://twitter.com/BretDevereaux/status/1359574074326982664)

Because the only effective language for communicating with the past is the language that the people of the past used, if those languages die then their stories and knowledge dies with them

Language is culture, and language is identity