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"Ur-religions" would probably be more appropriate. There are a couple of good review papers here and here. These models still suffer from a big problem though.
Back when I was 10 or so, and first started "studying" (as it were for a 10 year old) ancient myths - egypt, "classical mythology", aztecs - I used to wonder "what if we got it all wrong, and none of it is about gods." That, and I'd look around at the real world we live in today and say "and what if we walked into Denver from 2000 years in the future, and found structures, random selections of the variety of writings that we would ahve to deciper. But we walked in assuming that we were a people beholden to gods and highly religious, and the line "religion was part of every day life, you could not seperate one from the other" as we say so often now.
If we had that preconception, does that mean we would be clouded and call the Bronco's stadium a "temple?" Would we point out the big giant horse and say "oh, look, a fertility god!"
I had my kids write about this every year, so they could understand how easy it is to bias what you see with what you think you will see. I still am not convinced that the pyramids are not just giant mathmatical objects used to teach kids their shapes.
Check out Guthrie on Paleolithic art. Says pretty much the same thing. The goddess stuff seems to be even worse to me, considering that some of the figures were found in what were prehistoric trash heaps. So they chucked their goddess in the garbage, really?
And I'm not saying I believe or don't believe this. I have a hard time thinking you carve elaborate stautes like at goblke tepe "just cause". But i think you HAVE to bring that option to the table, when talking about what something "might be for" "might mean".
I do think religion is often our best guess, but i don't think it "must" be the answer, the way I see it most often talked about. My gut reaction for why i suspect most things are religion, even paintings on walls, is that every so called "primative" culture we know of or have studied, who survived into our western "modern" world, did indeed mystify most things, to some levels. but at the same time, not necessarily to the level we think. buffalo are sacred, as they are part of the natural world, but they were not gods to be worshiped. The earth (in native lore) was not "mother earth", that term was imported by the west, and adopted INTO modern new-traditional cultures.