Prometheus and Pandora

I believe that this myth is another example of Judeo-Christian religion sharing stories with literature from other cultures. While creation is different in Greek mythology than the Torah, the story of Noah's ark, is this time exactly the same. In Greek mythology, Zeus decides to drown the world and kill all the humans for behaving badly and being bad people. In the Torah, Hashem(God) decides to drown the world for the exact same reason. I am not saying that the Torah stole the flood story from the Greeks because the Greeks came after. However,why has monotheism thrived while the stories are exactly the same? Why has polytheism dissapeared? Why believe one and not the other? In fact, I think it is much cooler to believe in a god for every aspect of life than only one. The more the merrier no?