It is possible to make some sense of this, enough for an answer to be attempted, after magnifying and pulling together some ideas from the comments.
At least everyone will agree that's the One Ring in the palm of the hand.
On the left that's almost certainly Shelob, zooming shows a hairy spider-body behind the oddly human face, with a suggestion of longer legs on the left. So from context that's Sam or more likely an orc running towards an unconscious Frodo. The unearthly flowers may be inspired by nearby Morgul Vale.
Wide flats lay on either bank, shadowy meads filled with pale white flowers. Luminous these were too, beautiful and yet horrible of shape, like the demented forms in an uneasy dream; and they gave forth a faint sickening charnel-smell; an odour of rottenness filled the air.
A very passable Minas Tirith at upper-left under the text, with a canonical seven levels and tower of Ecthelion.
Yes, that really is Sauron at top-right behind behind the mountains of Mordor, commanding thirteen riderless fell beasts. Canonically, this isn't too bad, he must have had some breeding stock; after Legolas kills one with an arrow a replacement steed is found for the Nazgul, they aren't left mooching around for the rest of the novel. (We can discount other suggestions of Saruman and the spirit of Caradhras as they have no connections to fell beats.) It's certainly not how I picture Sauron, but he is only vaguely described.
Given that an ethereal Sauron is already in frame and that it doesn't have a pupil I'm going to discount the idea that the orb on the hill is the eye of Sauron. It could well be a Palantir, presumably Denethor's as it is behind Minas Tirith. The Stone of Erech is another possibility but this was a relatively minor story element.
The knights on the right are rather generic but the Rohirrim are the best fit. There is a fallen figure between the two horses so we are probably looking at the Battle of the Pelennor Fields in front of Minas Tirith.
But the white fury of the Northmen burned the hotter, and more skilled was their knighthood with long spears and bitter. Fewer were they but they clove through the Southrons like a fire-bolt in a forest. Right through the press drove Théoden Thengel's son, and his spear was shivered as he threw down their chieftain.
We could plausibly be looking at Théoden, although that's clearly a lance rather than a spear.
The two figures below the horsemen are the biggest mystery. Is one helping the other up? Are they having a symbolic tug-of-war with a very short rope? There is also a third figure obscured by a finger, also braced, perhaps pulling on another person. And what is that weird mound behind the little finger? Some beetle-creature? The Witch-King in very elaborate armour, with Merry stabbing him from behind?
I do have a suggestion, I think it's Old Man Willow re-imagined as a beetle-like creature. If you look closely there are four figures dressed identically to Frodo at bottom-left, Frodo and Sam are rescuing Merry and Pippin.
The artwork, like the album itself, is 'inspired' by LotR. Some elements are directly lifted whereas are loosely interpreted. @Turbo found the name of the artist, Jane Furst. Her wiki entry says:
Her work draws upon an interest in artists from the distant past, for example Northern Renaissance, from whom she borrows images, and also the study of natural form.
Which explains why a couple parts of the image allude to renaissance paintings, as pointed out in the comments. The unconscious, half-naked Frodo is taken from Mantegna's Lamentation of Christ, matching Frodo's role as a heroic martyr. The battling knights come from different parts of Uccello's Battle of San Romano.
It would be interesting to hear the artist's intent, but I think they are trying to convey something of the sweep of the story. We have scenes malign supernatural powers, struggle, fellowship and sacrifice. It's not a typical Tolkien calendar scene such as 'Gandalf vs the Balrog'.
