Unlike Ents, Tom is un-allied & doesn't even articulate that there _are_ sides (ents are on no-one's side b/c no-one's on their side). Tom is a reminder from an earlier age (or race??), older than virtually everything else. Unlike hobbits, he _knows_ evil.
In response to Bombadil, Tolkein said "he is not important to the larger narrative (like Sauron or Theoden), but perhaps an important component who serves a purpose to the narrative". Eric says: needed a transition between Hobbiton and Bree, Tom is comfortable enough to Hobbits at this early in the story. Tom _could_ have taken the ring to Mordor, but would The Earth do that? Hobbits would have been too shocked if they just arrived at Rivendell; Old Man Willow shows that evil exists outside of Sauron, sometimes trees are _just_ bad!
Hobbits like "nature controlled" (the Garden), Tom Bombadil shows uncontrolled nature, w/potential dangers!

Ch. VI, Merry says Old Forest is queer, _alive_, "the trees do not like strangers". remember the elves went into Fanghorn long ago & "woke up" the trees; Shire trees are "domesticated".
Old Forest trees re-arrange the paths, drop things on intruders, "attacked" the hedge & Hobbits _fought_ them (p. 109), burned many trees & they became unfriendly.
_That_ story shows these "peaceful" hobbits have a fear of being observed (by trees) & capable of intense aggresion in the name of maintaining Hobbit-lifestyle of being hidden.
"Heroism can come in different packages", LotR is about what Sauron _overlooked_,, hobbit life is about stealth.
Trees use centripetal force pushing hobbits to Tom Bombadil in the center (from the Old Forest, into the W.W. Valley, into Tom Bombadil).
Bombadil is a "center of queerness". Old-Willow is the first evil Hobbits see, showing them _some_ trees are evil, thus _some_ men can be evil (but not all are). this is instead of meeting Strider first & being afraid that _all_ men are evil
"evil can come in all packages, even close to home".
[p.118] Frodo's cries are drowned out by Willow & Wind, Tom arrives _belting out_. He sings like a chiding parent, & his mere existence of _his_ reality replaces whatever was happening.
* Barrow Wights: Barrow Downs = Anglo-Saxons buried in a mound w/their possessions [see Beowulf pt. 3]
Tom literally just sings a song (& is summoned by a song) & banishes the wights, plus opens a hole to let _light_ inside (p. 145). Exorcises the wights' curse by re-circulating their wealth, instead of being a hoard [of wealth] & remaining whole, piecemeal taking objects & _using_ them de-anchors them [from the curse of greed]. Unlike Beowulf's dragon-hoard, which was also treasure buried w/a dead man & took a curse through _not_ being re-circulated.

*Goldberry	[p.123] describes Goldberry's appearance, Tom's main practice is collecting lilies for her: early image of courtly love, repeated w/Galadriel. The hobbit's first "crush" on a fair beauty; the Hobbits being speaking more galantly.
- How do LotR women operate? "inspiration" for the men, like Guenevere. Goldberry inspires Tom as a courtly-romance love, inspires hobbits as a beauty worth protecting the earth for.
Imagine  if they had encountered the evil in Bree before the respite of Tom Bombadil!