The essence of spirituality is not supernatural. It comes from humility – acknowledging something larger than one's self.
There's a commonly repeated factoid that the human brain is the most complex object we know of in the universe. The complexity comes from the way the neurons cross-connect to each other through synapses.
But this takes the brain out of context. Human babies take years to become self sufficient, compared to minutes or months for other animals. No other animal is dependant on its parents as long as humans; and the reason why is because of our huge brains. They eventually become a great advantage, but at first they're a great drawback.
The brain was only able to become the complex object it is because of human social behavior. The tribe all cooperated to raise children; but also the language they spoke to each other contributed to the growth of the brain.
Far more complex than a single human brain is the network between all human brains. With some effort, a person can move to a foreign country, learn the language, and interact with the culture. But through connections, you're only a handful of degrees away from most of the billions of people on Earth right now.
Connection multiplies the complexity of the brains that interact. Anyone who's ever seen the process behind creating a seating chart for a dinner event knows how fast the complexity goes up.
No matter how great one person is, they are miniscule compared to the sum of all people.