What is the origin of religion?

Did religion develop during prehistoric times simply to explain things that could not otherwise be answered? Like worshipping the Sun God, or God of the Harvest, or God of the sea. Is this really how Paganism developed? If so, and there really is one true God out there, then why did he wait so long to reveal himself, and why did he only originally reveal himself to the Hebrews ignoring all other populations of the earth, while allowing Paganism and other religious beliefs to rise? None of this makes sense when stepping back and looking at the eternal plan of salvation.