"Many Partings" - Jacob's Thoughts

We've touched lightly on this point before, but my memory remains hazy, and what's more, the text never once makes it explicitly clear: what the heck is the deal with the Rings, anyways?  What exactly were their powers?  What was their initial purpose?  Why were they forged in the first place?  What benefit did they offer?  Why are the fates of so many races now tied directly to them?  Why exactly is it that not only the Elves, but the Maiar themselves, must needs diminish because the One Ring was destroyed?  When our homeward-bound party encounters a degraded, begging Saruman on the road, he spitefully rails against Galadrial and Gandalf that his one solace is that they tore down their own house when they tore down his, too.  How so?  What exactly does he mean?  Galadrial and Gandalf don't exactly contradict him.

The Elves, likewise, prepare to emigrate across the seas now that the power of the Rings are destroyed--though why they must merely relocate away from Middle-Earth, as opposed to go extinct or ascend to some other spiritual realm or whatever (unless the Grey Havens are some sort of obscure euphemism for death that I'm missing), I remain totally in the dark about.  Why are their destinies tied up with the Rings, in a manner that, say, those of Men are not?  The Hobbits never had any Rings of Power, so I understand them being unaffected by the equation--but the race of Men sure did, and not only are they not negatively affected by the One Ring's destruction, but they rise to dominate the Fourth Age.  Again, why??

There's just this bizarre dream-logic about everything concerning the Rings--but even that cop-out explanation won't fly, since everything else in this text is presented as grounded in a material world with a lived history and real consequences. The Rings are integral to this world, but Tolkien stubbornly refuses to ever articulate why. When the One Ring was simply the last horcrux of the Dark Lord (to use an incredibly anachronistic analogy), I was willing to just go along with it; but if the text is going to insist on foregrounding the broader web of relations between the various Rings of Powers, then I have no choice but to call the text out on its own maddening vagueness.

The fact that the destruction of the Ring has all these other collateral effects is presented by the text as self-explanatory, when it is not.  Everything about the Rings remains as opaque and inscrutable in the end as they were in the beginning.  These are not mere pedantic side-points to fuss over, but ostensibly the entire focus of the series--it's entitled The Lord of the RINGS for crying out loud!  Yes, yes, I'm sure that The Silmarillion and Unfinished Tales and 12-volume History of Middle-Earth and whatever maps everything out much more explicitly; but frankly, I shouldn't have to do a bunch of extracurricular homework to understand the underlying mechanisms of the novel I've already agreed to read.  Of all of the numerous exposition-dumps I've waded through across this series, could there not have been at least one, somewhere, somehow, that clearly lays out for me what the heck the deal with the Rings are?

Don't get me wrong, I've still enjoyed the journey over all, it's a pleasant series to read; but my flailing ignorance about the Rings--an ignorance induced by the text itself--is really starting to bug me.