Here's a simplified explanation:
* Language is constantly evolving: Languages change over time, with new words being added, old words changing meaning, and grammatical structures shifting.
* Proto-Indo-European Roots: English, like many European languages, traces its roots back to Proto-Indo-European, an ancient language spoken thousands of years ago. This language had concepts of nouns and adjectives, which were passed down through various branches of the language family.
* No Single Inventor: The idea of nouns and adjectives (and other grammatical categories) developed over time as people used language to communicate and describe the world around them.
Think of it like this: If you were to trace the lineage of a word like "tree" or "green," you'd find that its roots stretch back to Proto-Indo-European and beyond. No single person is credited with inventing these concepts, just as no one invented the wheel or fire.
The development of nouns and adjectives was a gradual process of linguistic evolution, driven by the needs and innovations of generations of speakers.