Is spirituality natural? That the early humans were enamored by light, fire, rain, thunder, etc., and founded the origins of spirituality in it, is the observation I encountered the most. I find no reason to think so.
I think the discovery of lenses with the property of magnification, initiated our journey into the spiritual world. Because that is when humans would have come to realize that there is something more than what we can see, everywhere. And spirituality is all about transposing that into something which is more in sync with our life. As humans succeed in bringing more and more abstract ideas into the realm of the real, the person of god continues to change its appearance. From fire, earth, and water, to faraway places, planets, and space, and to more abstract propositions of each, the concept of god fluctuates, keeping a safe distance with, or moving in the shadow of, the current umbrella of knowledge.