Very first Religion?

[Psalm 23]

Probably some kind of anamsism, a belief that rocks, trees, animals, rivers have spirits.

When early man was frightened and confused by the random manner in which his universe tries to kill him he would have sought to appease it.

Probably some lazy, cunning son-of-a-bitch found that by dressing up in animal skins and talking funny he could frighten the tribe into feeding and looking after him.

Thus was born the first priest.

Human-kind has been worshipping a god or goddess of some sort as far back as Historians, Archaeologists, and Scientists can study.
They have evidence that the neanderthals worshipped a god.

The ancient Egyptians used to do certain rituals to prevent the world from coming to an end. They also believed one of their gods was the Sun. Now we know that is untrue, and quite silly. Unless God is a huge ball of hot gases. But wait, the bible says, "God created the Sun." So does that mean God created the Egyptian gods?

[Edwardo Piet]

Unless God is a huge ball of hot gases. But wait, the bible says, "God created the Sun." So does that mean God created the Egyptian gods?

Actually Yahweh, the holy spirit or Jesus as the son of God is more absurd if anything. Because there is actually evidence of the existence of the sun. There isn't of "God".
Although of course the probability that the sun is a supernatural God is basically zero too.

[downbeatplumb]

I have an alternative 'first religion' see what you think.

I put for your consideration SUPERSTITION.

Every body does the old 'if I get this balled up bit of paper in the bin I'll have a good night' game.

Silly and we know it, but Ogg the caveman has no reason not to believe, especially if for some reason his musing has positive reinforcement.

Religion is just a bunch of superstitions formalised and layered with traditions and dogma.