>after reading about the creation of the universe in both the Bible and Edith Hamilton's Mythology, it appears that both are quite similar.<

I checked out Edith Hamilton's 'Mythology' on Amazon. It is based on the Greek and Roman myths.
Roman civilisation drew heavily from Greek civilisation. Christianity originated in Rome. All are part of 'Western' civilisation.
I'd say similarities are not so much coincidence as signs of common ancestry. Perhaps you should explore the creation myths of some other civilisations? Native American? Chinese? Aborigine? I don't know any of them in enough detail, but I think they're more different.

BTW, I believe the 'great flood' in many western mythologies including the Bible is meant to be based on the creation of the Meiterranean. Originally dry land below sea level, then the Straits of Gibraltar 'opened' and there was a very big waterfall for a while.