In the Lord of the Rings and his other writings Tolkien speaks of races and peoples to mean what we would call different species. The major division between the Children of Illuvatar was between the Elves and Men (the Eldar and the Edain). Within these two groups there were further subgroupings that I guess could best be described as tribes or nations. But the differences between Elves and Men are profound. The Elves do not grow old. Therefore, unless they are killed by accident or illness they can live indefinitely. And even when they die their spirit is constrained to remain within the Realm of Arda which is under the control of the angelic powers, the Valar. In fact, it is hinted at by Tolkien that eventually the spirits of Elves that have died will be returned to life in Arda after some very long time. Men are mortal just as humans are on Earth. In Tolkien’s theology men do not remain in Arda after they die. Their spirits leave Arda altogether and return to Illuvatar outside of the jurisdiction of the Valar.
What Tolkien seemed to be mirroring with the Elves and Men was the distinction between men who lived before the Christian era who had no chance of redemption from the Christian perspective and those who lived after. The Elves would be like the Valar in a way. They could serve Illuvatar and share in the smaller creation that was Arda but within Arda they were not in direct contact with Illuvatar. Men were meant to escape Arda after their lives and then return to Illuvatar. Despite the profound differences between Men and Elves Tolkien allowed for the possibility of love and even children between Men and Elves. But what would the children be, deathless Elves or mortal Men? Tolkien decided that they would be permitted a choice. If they chose to be Men then that was a final choice for them and their children. But if they chose to be of Elven-kind then their children also had the choice to make and in the same way. Now what this means to me is that any child of a Man would always have the choice to choose to be Human. And I think this is because the Fate of Man is the higher fate. The Elves are halfway between Valar and Men. And despite the tremendous power of the angelic Valar their fate is less than that of Men.
Then there are the Dwarves. According to the Silmarillion the Dwarves were not created by Illuvatar but instead were the unsanctioned creation of Aulë, one of the Valar. When Illuvatar spoke to Aulë about what he had done Aulë realized that what he had created weren’t independent beings but only shadows of himself, puppets. Aulë was about to smash them when he saw that Illuvatar had turned them into living beings with souls of their own. This makes the Dwarves sort of adoptive children of Illuvatar. I believe they are like the Elves in being bound to Arda and under the authority of the Valar. And they are odd in other ways and always seem to be at odds with the natural children of Illuvatar. They are not naturally evil but the properties that Aulë endowed them with put them at odds with Men and Elves.
The Hobbits are sort of like nature spirits that inhabit English folklore like Puck or Robin Goodfellow but based on Tolkien’s characterization in his books I have to say I believe the Hobbits are human. They are mortal and beside their stature they are in all ways human. Maybe Tolkien intended to make them bound to Arda like the Elves and Dwarves but based on the Hobbits we meet I wouldn’t think they should be left out of human heaven. They’re just too human.
In the Silmarillion Tolkien tells us that the Orcs were made by Morgoth by capturing Elves and corrupting them through his evil influence. This always made me wonder then if Orcs also did not die of old age. We are never shown any female Orcs which is probably a blessing but I assume they must exist. The idea of a corrupted race is a little hard to understand theologically. For instance, it seems possible that just by chance, an Orc might be born that wasn’t particularly evil. And if he managed to escape the evil influence of his tribe might live a virtuous life. I’ve heard people talk along these lines and mock the idea of “good Orcs” and based on what we see in the Lord of the Rings it does seem patently ridiculous but since Tolkien was a Christian writer, I’m sure he thought about that possibility. Suffice it to say that no “good Orcs” ever show up anywhere in the Tolkien tests.
Dwarves and Elves are pretty standard creatures of Northern European folklore and Tolkien adapted as needed for his use but one of the most original characters that Tolkien place in his Middle Earth was the Ent. They are the “Shepherds of the Trees.” They resemble trees. They are gigantic in size and have great physical strength. Their ability to rend stone is compared to a much-accelerated version of the action that roots have for infiltrating and cracking stone that they come in contact with. Ents also appear to live indefinitely unless killed by violence. But they can become senescent and become completely tree-like. It seems that the Ents must be another race of creatures like the Elves that are restricted to Arda forever. But from their description in the Silmarillion, they are never described as Children of Illuvatar. Possibly Tolkien never left any notes about the status of the Ents because he invented them later on than the Elves and Dwarves. Whatever their place in the theology of Middle Earth Tolkien designed them with a distinctive and entertaining character. They are extremely slow and methodical in their actions and extremely long winded in their method of speech. They think of normal action by any other race as extremely hasty. This must be to mimic the immobility and permanence of trees in the landscape.
And finally, the last of the other major peoples of Middle Earth are the Trolls. Trolls are a well-known creature of legend but how Tolkien fits them into his creation is not well defined. I can remember hearing the explanation that they were Ents that were twisted by Morgoth into evil creatures just as the Elves were turned into Orcs. Honestly this seems singularly unconvincing. There doesn’t seem to be much Ent-like character to Trolls. But I haven’t heard any other explanation so I’ll just leave this as a loose end. In addition to being evil the main character trait of Trolls seems to be stupidity. But they are enormously strong and tough so they come in handy for war scenes when something special is needed.
Based on the status of the various races of speaking peoples in Middle Earth what it seems is that Tolkien has Christianized the folklore creatures of Norse mythology by giving them a place in the Genesis story of his world, Middle Earth. It is not at all clear what the final status is of the Elves, Dwarves, Ents or even the Orcs and Trolls. They seem to have souls like men and are judged on their deeds, good and evil. But it is far from clear whether even the Elves can gain Paradise in this theology. Instead, they seem to be permanently attached to sub-creation of the Valar, the Kingdom of Arda. And that may be Tolkien’s intention.