tolkiens legendarium - What is the true origin of the orcs?

There are a bunch of theories about the true origin of the orcs. Tolkien tried out a few different origins for his Orcs throughout his life but died before he could fully revise The Silmarillion with his final view on their origins and nature.

There is a list of origins proposed by Tolkien(source):

1. Made of stone and slime through the sorcery of Morgoth;


2. East Elves, where The Silmarillion contains a suggestion that Orcs are descended from East Elves captured by Melkor, their minds and bodies distorted and corrupted.


3. Sentient beasts, another of Tolkien's theories proposes that Orcs may have begun as soulless animals of vaguely humanoid shapes, empowered by the will of the Dark Lord (Morgoth) and learning language only as parrots do.


4. Fallen Maiar, there are hints in the History of Middle-earth series of books, (especially in Morgoth's Ring in the section "Myths Transformed"), that some Orc leaders, such as the First Age's Boldog, or the Great Goblin encountered by Bilbo and the Dwarves, may in fact have been fallen Maiar which had taken Orc form.


5. Corrupted Men, while Tolkien at some point saw all Orcs as descended from the original corrupted and tortured Elves, later comments of his indicate, according to Christopher Tolkien in Morgoth's Ring "Myths Transformed" text X, that he began to feel uncomfortable with this theory. At about the same time he removed the references to the Thrall-Ñoldorin, he also began searching for a new origin for the Orcs. It seems Tolkien wanted to change the origin of the Orcs to make them corrupted and twisted Humans.



6. A mix of corrupted Elves and Men, A late idea of Tolkien seems to be that Orcs (or Orks, showing the late spelling change) had a mixed origin of Elves and Men.


7. Some cross-bred with Men, Tolkien also suggested that Men were cross-bred with Orcs under Morgoth's lieutenant, Sauron (and possibly under Morgoth himself). The process was later repeated during the War of the Ring by Saruman. This possibly refers to the way the Uruk-hai and the Half-Orcs were created, in The Lord of the Rings.

Of all these theories, which is the most accepted, and which did Tolkien agree with the most? I always thought that orcs were made of East Elves, as explained in The Lord of The Rings, but the story goes beyond this, there are the stories in many other books that explain different things.

What can you tell me about this?

Answer

Perhaps the best answer is why do we need to define Orcs as having a single origin? It is possible that all of these answers are correct or none of them are. Tolkien may have decided there may have simply been a number of ways Orcs came into existence. From purely a scientific point of view, there have been at least three different hominid species to have come into existence on Earth, why would there be only one way to make an Orc on Middle-earth? In fact, all of your definitions could explain why there were so many different kinds of demi-human life on Middle-Earth.

Consider:

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  No being but Ilúvatar could truly bring anything to life. The Dwarves were a gift to Aule, who wanted to make life but could not, and he was a Valar. After crafting them only Ilúvatar could give them life.

  
  


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  Morgoth wanted to make life and he was the second most powerful of the Valar. Since he could not, it was rumored he transformed the Elves into the First Orcs. Seeing how he eventually created an entire army to wage war against the Valar, he spent the bulk of his time re-crafting Life to serve as his agents.

  
  


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  There is no reason other Valar or Maiar could not have done the same thing, that is, corrupt a living being and turn it to a new and unsavory purpose à la the Uruk-hai Orcs.

  
  

Since there were also goblins and other demi-human life forms in Middle-earth, corrupting Life may have simply been making the best of a bad situation where Beings who were keen on making Life would have to corrupt what source material was available since creating new life was simply the province of the One primal deity of the Middle-earth universe.