Traditionally in D&D there haven't been too many varieties of natives to the Ethereal Plane
This absence of animism in early D&D relates to the Tokienism of reinventing nature spirits as if different human ethnicities. (A kind of euhemerization.) So elves and goblins and so on become construed to be humans of flesh and blood, with their own cultures and languages. Normally, these elves and goblins would be features of nature whose manifestations would be speaking whatever languages the humans are speaking.
However, with 4e and 5e, the introduction of the Feywild and the Shadowfell is a place for nature spirits. (Corpses count as features of nature that are no longer living human bodies. Death is a kind of shapechanging. But the soul or at least an aspect of the soul remains with the corpse.)
4e originally lacks the Ethereal Plane. The Ethereal and Shadow remixed to become the new Feywild and the Shadowfell. The Fey have illusion and teleport like Shadow does, while the Shadowfell has the overlap like Ethereal does. Both planes are a remix of the previous two planes.
But then 5e reintroduces the Ethereal Plane, so now Fey, Ether, and Shadow coexist. They relate to each other yet are distinct from each other. I view the Ether as a mix of Positive Fey and Negative Shadow.
Now both Ether and Fey are places of nature spirits, or at least can and should be. Ether is more the Material Plane itself, while the Fey is more an idealized version of it.
So far, in 4e and 5e, the descriptions of the Feywild tend to disconnect away from the Material Plane. But this is bad for animism. Animism is necessarily the Material Plane itself. Even when a shaman goes on a dreamlike spirit journey, the soul (mind, spirit) of the shaman is still traveling thru the Material Plane and visiting places within the Material. For the Feywild to relate to animism, the Feywild must emphasize how it overlaps the Material Plane, and especially how Fey creatures can observe Humans going about their ordinary activities.
With the 5e Ethereal Plane, the Border Ether explicitly overlaps the Material Plane and plainly observes it. But now 2024 needs to start thinking about who is there in this overlap. Essentially, every "soul" that is "outofbody" is moving thru this Ethereal overlap.
Ether is force. Gravity is ethereal. The Border Ether is part of the Material Plane and its ethereal forces emanate from matter and pervade matter.
, a lot of it has been Incorporeal Undead
A "ghost" is something like a soul that is tainted by Shadow so that it can "rest in peace". Alternatively, some souls might become Fey rather than Shadow.
The soul has different levels. The bodily aura is the part of soul that emanates from the material body. It is the life of the body and the "ki". The ghosts relate to this bodily, where even the corpse retains a remant of it, and necromancy manipulates it.
The spirit is the part of the soul that can separate from the body. It is the self-identity and can learn, grow, and evolve. It is the magical influence, and the soul of an artist − and Bardic magic. The influence of the spirit of a person can travel outofbody thru the Ethereal Plane.
The consciousness sounds slightly paradoxical, because it is the consciousness itself and not any particular thing that one is conscious of. This relates to Buddhist enlightenment and so on. It is indestructable and unshakable because it is nothingness. This is the part of the soul that can exist eternally within the Astral Plane. And there, the consciousness can experience the realm of ideals, paradigms, symbols, linguistic structures come to life within the thoughtscape.
, a Humanoid species called the Nathri which never had the same appeal as the Gith, Phase Spiders, the annoying Ethereal Filcher and the Ethergaunt which probably are more likely to be some form of Aberration (I really wish they returned to D&D after 3.5e) based on the appearances.
Perhaps the creature type Giant can mean exactly a Elemental of the Material Plane whose soul roams the Ethereal.
The Ethereal Plane does need some more work done on it, and I say that as someone who's very much into the Great Ring cosmology and Planescape.
5e is still in the process of sorting out the Ether, Fey, and Shadow. But I like the stuff it is already doing and where it is heading.
They probably need to throw in a bunch of the Region of Dream or Spirit World stuff into the Ethereal Plane, now that there's very much a niche for Shadowfell and Feywild.
D&D does have tradtions about the place of Dreaming or Dream. But where dreams happen remains vague.
A more modern sense would have a dream be a mode of cognition, thus strictly within the Astral Plane as part of its thoughtscapes.
However, a premodern concept of dream would be the soul leaving body every night to journey into the spiritual worlds where dreams happen. In this case, the dream is more physically existing, and more like the Ethereal than the Astral.
Some traditions imagine the Feywild as the Dreaming, or similarly in Eberron the place where stories come to life, like a kind of "Twilight Zone". If so, these Zones might be the Domains of Delight that are within the Deep Fey. 5e similarly imagines the Domains of Dread, like Ravenloft, to be a place of gothic horror stories that appear real but are illusory. The only person that actually exists there is the soul of the Dread Lord who is tormented by these inescapable illusions.
The Deep Fey and the Deep Shadow can have their respective domains be Positive dreamscapes and Negative dreamscapes.
