Where do elder scrolls come from. What are they exactly and who made them?

The players kind of make them. Some hold our stories others hold different ones. There is a countless amount of Elder Scrolls. As seen in the Mainquest Skyrim's the Dragon Elder Scroll had the story of the 3 warriors who tried to kill Alduin. Every scroll is different. As seen in Dawnguard They have a lot of purposes.

I think this issue came up in a previous thread, but I can't remember what the title was. It might have been the one that asks about why the Graybeards called Elder Scrolls "blasphemies." A more accurate explanation of what they are can be found there, IIRC, but I'll try to put one here as well:

Elder Scrolls are objects that can reveal possibilities. That theory of some multiverse full of universes that are all the same except for one change in the past (coupled with "butterfly effect"), an infinite number of which exist because there are infinite choices for an infinite amount of people (or living beings, anyway), is probably the best comparison. The Elder Scrolls know all of that--not only the possible futures, changing as the choices faced by living people change, but it can also record all the possible pasts that were swept away because the choices required for them were not made. The turn of phrase "writing an Elder Scroll," for instance, roughly means "to make history" in the sense that someone did something important enough to be put in the record books. Less roughly, and more accurately, it means "doing something that eliminates other possible futures," or even "changing the world in a way that would not have happened had other choices been made." Same idea, but more specific, I think.

All this assumes that time is linear, and options in the past can't be reused should a certain Dragon go on holiday (willingly or not).

Again, a better description will likely come from another source, but this is as well as I understand the concept myself. As for who made them, you might as well be asking, "Who (or what) made atoms?" I think there were some fairly good explanations for that in the other thread as well, but I'm not smart enough to understand half of them.

That sounds pretty good to me.

I like how the cosmic elements of the TES universe play around with some scientific truths (like the scrolls could be quantum in nature, while gods are planets, etc).. I can see why some of the more in depth lore touches on futurisitic, sci-fi settings, and not be totally out of place. Since the fantasy version of TES has a kernel of science fiction about it as well. I don't get into all of that, but it's interesting.

Along those same lines, my first forays into serious lore outside of the Tribunal propaganda I'd learned years ago came when I looked up something on the UESP, and found the "unofficial" source Nu-Mantia Intercepts. From that, I found other bits of Kirkbride's work, at which point I posted something on Facebook to the tune of, "Only a few people could turn a somewhat-regular fantasy into incomprehensible science-fiction. I think I found one of them." That's not to say that incomprehensible is bad, of course; that's one of the reasons that I read every post that I can wrap my head around on this forum, trying my best to stretch my understanding so that eventually all of it will make sense to me. Kind of. Maybe?

In the written words of Septimus Signus:

"Imagine living beneath the waves with a strong-sighted blessing of most excellent fabric. Holding the fabric over your gills, you would begin to breathe-drink its warp and weft. Though the plantmatter fibers imbue your soul, the wretched plankton would pollute the cloth until it stank to heavens of prophecy. This is one manner in which the Scrolls first came to pass, but are we the sea, or the breather, or the fabric? Or are we the breath itself?
Can we flow through the Scrolls as knowledge flows through, being the water, or are we the stuck morass of sea-filth that gathers on the edge?
Imagine, again, this time but different. A bird cresting the wind is lifted by a gust and downed by a stone. But the stone can come from above, if the bird is upside down. Where, then, did the gust come from? And which direction? Did the gods send either, or has the bird decreed their presence by her own mindmaking?
The all-sight of the Scrolls makes a turning of the mind such that relative positions are absolute in their primacy.
I ask you again to imagine for me. This time you are beneath the ground, a tiny acorn planted by some well-meaning elf-maiden of the woodlands for her pleasure. You wish to grow but fear what you may become, so you push off the water, the dirt, the sun, to stay in your hole. But it is in the very pushing that you become a tree, in spite of yourself. How did that happen?
The acorn is a kind of tree-egg in this instance, and the knowledge is water and sun. We are the chicken inside the egg, but also the dirt. The knowledge from the Scrolls is what we push against to become full-sighted ourselves.
One final imagining before your mind closes from the shock of ever-knowing. You are now a flame burning bright blue within a vast emptiness. In time you see your brothers and sisters, burnings of their own in the distance and along your side. A sea of pinpoints, a constellation of memories. Each burns bright, then flickers. Then two more take its place but not forever lest the void fills with rancid light that svcks the thought.
Each of our minds is actually the emptiness, and the learnings of the Scrolls are the pinpoints. Without their stabbing light, my consciousness would be as a vast nothingness, unknowing its emptiness as a void is unknowing of itself. But the burnings are dangerous, and must be carefully tended and minded and brought to themselves and spread to their siblings."

http://www.imperial-library.info/content/ruminations-elder-scroll

Make sense of that and you'll have your answer.