Definiteness, indefiniteness, singular and plural forms, and masculine and feminine agreement may carry different scopes in context. A generic noun can refer to a whole class; a plural may have a contextual subset as its referent; and the antecedent of a pronoun can sometimes be understood by meaning rather than mere proximity.
When the Qur’an uses “al-insān,” ask whether it denotes a particular person or humankind as a class in that setting. Similarly, “al-nās” should not automatically mean every human being in every historical scene.
To identify a pronoun, consider gender, number, sentence structure, semantic suitability, and the whole passage. An unusual agreement need not be treated as an error in the text.