> There are many magical creatures in Middle-Earth without a described source, which to me makes the whole story feel more magic.
As far as I know, this isn't true. Virtually all creatures and major characters in LotR have a clear source in the lore Tolkien developed. Of course, only a fraction of this lore is in LotR itself, and the rest was in notes published after his death, e.g. in The Silmarillion.
That's precisely what makes Tom Bombadil such an eye-catching exception.
I disagree. Tolkien leaves plenty to the imagination and often alludes to histories or events which he doesn't bother explaining elsewhere.
>'We cannot go further tonight,' said Boromir. `Let those call it the wind who will; there are fell voices on the air; and these stones are aimed at us.' `I do call it the wind,' said Aragorn. `But that does not make what you say untrue. There are many evil and unfriendly things in the world that have little love for those that go on two legs, and yet are not in league with Sauron, but have purposes of their own. Some have been in this world longer than he.'
'Caradhras was called the Cruel, and had an ill name, said Gimli, `long years ago, when rumour of Sauron had not been heard in these lands.'
Aragorn explains that there are evils older than Sauron and we get the sense that the mountain itself may hold a prejudice against the company but this is never explained or developed elsewhere. Caradhras the Cruel doesn't appear elsewhere either. I'll add that the film unfortunately dispels this uncertainty from the original novel.
> Aragorn explains that there are evils older than Sauron
Caradhras contained Durin's Bane, a Balrog, which sufficiently explains this comment. There are certainly many evils predating Sauron, notably Morgoth.
As far as I know, this isn't true. Virtually all creatures and major characters in LotR have a clear source in the lore Tolkien developed. Of course, only a fraction of this lore is in LotR itself, and the rest was in notes published after his death, e.g. in The Silmarillion.
That's precisely what makes Tom Bombadil such an eye-catching exception.