From
Letters of J.R.R. Tolkien, letter 144:
And even in a mythical Age there must be some
enigmas, as there always are.
Tom Bombadil is one (intentionally).
Aulë who teaches the
Elves smithcraft and has little concern with living things, unlike
Yavanna, is not much like Tom Bombadil.
Now if
Tom appeared as a smith, or was even shown to have an anvil somwhere around his place ....
But since
Tolkien apparently preferred not to classify Tom, not to fit him in precisely into his legendarium, any theory by anyone else is hard to take seriously.
Only Yavanna and
Oromë, not Aulë, are said to be unwilling to utterly forsake
Middle-earth, while Tom claims to have dwelt there since before the coming of
Melkor, before the first raindrop, much less the first tree.
Neither Yavanna or Oromë dwelt continually in Middle-earth. At the time when Tolkien was writing
The Lord of the Rings Oromë was still held to be a son of Yavanna born before the coming into Eä, but his father was not Aulë.
As to Tom being a
Maia (which would include all the leprawns etc. mentioned by Elwe Singollo, it is an argument from silence to assume that all
spirits found with Eä were
Ainur from without. There
may also have been spirits created alone with Eä, always part of it.
He might be the first spirit of some kind or other to permanent take incarnate form within
Arda, which would explain why is called “Oldest”.
Tolkien may have felt that Tom being an enigma was more effective aesthetically than unncessarily inventing a particular place and history for him (unless suddenly inspiration struck him).
As far as we know, it didn’t.
Note that River-woman,
Goldberry’t mother, appears faintly as a character in the poem “The Adventures of Tom Bombadil”.
Who would River-woman be, if one wants to make Goldberry one of the
Valar?
