As a university professor I sell what I know. - H. Russell Bernard

It is not necessary to argue that language diversity caused the evolutionary success of humans. We need only recognize that the knowledge generated by all those successfully adapting cultural groups over the millennia is stored in all those thousands of languages now spoken around the world.

Weren't humans domesticated by the requirements of the plants and animals themselves?

There are 63 officially recognized indigenous languages in Mexico, but there are at least 282 indigenous languages spoken in Mexico...We see the different languages in these families referred to as "varieties" or “dialects” in the literature. Nobody would think today of calling Spanish, Romanian, Catalan, French and Portuguese "varieties" of Latin.