I don't know if we "insist" the world is really linear. The attempt to make history and civilization linear or progressively one-directional is the anomaly in question. The natural cycles and feedback loops will likely win in the end and encompass linear societies, but this is just like life fighting entropy at the level of personhood. It's an existential rebellion that makes for intriguing dichotomies, such as that between the wilderness and artificiality. Again, that dichotomy may not be eternal or metaphysically basic, but neither does it seem fanciful.