I agree with everyone else, here, that the Greeks did not "originate" religion or the idea of it, but they did create their own religions. And there were many reasons.
Some of the earlier gods were symbolic for either actual individuals or groups in prehistory.
Take for instance the myth of Athena's birth. This could be an alternate version of Plato's Atlantis story, the latter of which came by way of Egypt.
The name "Athena" is thought by many linguists to be non-Greek in origin.
Her story begins with Zeus and his former girlfriend, Metis -- one of the Titans -- the wisest individual of all time. Zeus had heard that his children by Metis would one day overthrow him as king of the gods, so Zeus swallowed Metis whole. Later, Athena (already conceived), was born full grown from her father's head and wearing armor and carrying weapons. Ouch!
Compare these details to the story of Atlantis. Atlantis was the most advanced (wisest) nation of all time. Atlantis threatened to take over the entire world, but was swallowed whole by the sea. The refugees, perhaps many of them fleeing the capital (head) city, settled in Europe. They were fully mature as a civilization, carrying the weapons and armor needed to protect themselves.
This goddess compares favorably with the Etruscan goddess, Minerva. In many respects they are equivalent. The Etruscans spoke an agglutinative language with some interesting ties to Basque. It seems that the words for mother and father were very similar, but gender swapped. And yet, in the Etruscan pantheon, the god of endings and goddess of beginnings had names which matched by gender the Basque words for mother and father. It seems in some of the cultures founded by children of Atlantis, the switch from matriarchal to patriarchal society was accompanied with the term staying with the role rather than the gender. So, if mothers ruled, men became the new mothers.
It's also interesting to note that in Colchis (modern Georgia), where they also speak an agglutinative language with apparent ties to Basque, the word for mother is "deda," while the word for father is "mama."
Both Metis (late Atlantis) and Athena (children of Atlantis) were female, suggesting that both cultures were matriarchal. And when the princess of Colchis flew away on a golden dragon after leaving her second husband (king of Athens) after Jason of the Argonauts, she may have given us one more piece of mythology: a matriarchal group, ama-Atlan -- mother Atlantis (Amazon).