I saw that she ate a cookie. Ze at een koekje. Language is part of human cognition -part of the human mind . Linguists want to know about the human language faculty. The ability to learn, use and, when necessary, to create language, is part of the human biological make-up.
Language plays a role in human culture.
Storytelling Law, etc. The way in which we use language is influenced by our cultures. BUT The fact that we use language is biologically determined. Just as you learn to walk, you learn to talk. If the use of language were a cultural construct, there would be cultures without language.