low linguistic self-esteem is a sad consequence of unsuccessful teaching about language.

ratiocination

Such an idea might seem fascinating at first. But on closer inspection it loses any claim to be a scientific thesis.

linguist is interested in ascertaining what the actual grammatical constraints of the given language are.

phonetics (the production, perception, and acoustic nature of speech sounds);

Language is indeed changing and evolving all the time, but the process is extremely slow.

semantics (the systematic expression of literal meanings);

pragmatics (the conveying of meaning by uttering sentences in specific contexts).

But the key to what separates the cognitive powers of humans from those of all other creatures lies in the principles of syntax (sentence structure), semantics (literal meaning of sentences), and pragmatics (conveyance of utterance meaning in context).