> existing in nature and not made or caused by people : coming from nature

This definition really stems from man's early assumption that we are distinctly "different" from all other natural things.

But reality tells us otherwise: People are a part of nature; they are natural. It's easier to discuss in terms of what isn't the same instead of what is the same. And that is, we are the smartest known species (being the sole species with self-consciousness is still up for debate). Therefore everything people do is natural.