Words must express truth. Grammatical qualities are different as various cultures differ, but the basic facts of sex and number are much the same through the various language groups spread over a large area of peoples. Rules of expression, based on usage, were created, and the discipline of grammar was born. Some changes in language occur over long periods of time, but the basic elements remain unchangeable, even after concentrated efforts have been made to effect change. Within our English language, changed as it has in many ways through the passage of time and its exportation to every continent, certain elements remain the same over centuries of usage.
Many words are capable of a variety of meanings.
Consult the dictionary and see how one word can have many uses. Note how the context is so important to the meaning. The distinction between marked and unmarked is often found in all manner of contrasts. The generic, unmarked word usually includes the specific, marked word. The unmarked words occur entirely independent of sex or social status or even the grammatical forms, while the marked words have some restricting or specifying quality attached to them.