We are mother nature and mother nature is us. It's all intertwined. An iPhone is as natural as a banana (earth -> tree -> banana, earth -> human -> iphone). The unnatural would be, by definition, impossible.
Either humans are unique and non-animal, or we and all our works are as natural as anthills and bird nests.
> The way things are, the totality of all things in the physical universe and their order, especially the physical world in contrast to spiritual realms and flora and fauna as distinct from human conventions, art, and technology.[0]
Without this exception "natural" loses all meaning; nothing would be considered artificial because everything inevitably comes from the earth.