If there is only 1 God how did the Sumerians get so smart and know about pluto?

Wow, that's some powerful god. I know if I was the omnipotent creater of the universe, I'd make sure that a random bronze age society knew a random fact that was utterly useless to them. I wouldn't eliminate birth defects or disease, I'd just let them know about some random-*** almost-planet that is no help to their difficult lives whatsoever.