He's old, very old

Eldest, that's what Tom Bombadil is.

Edit: In Magic The Gathering, he's listed as a god.

The Legendarium represents the cultural perspective of the Noldor and the Men who adopted much of their cultural tradition. It's not an objective history, and some things that exist in the world, such as Tom Bombadil and Ungoliant, aren't really accounted for by the Noldor cosmology, even though these beings are known to them.

Similarly, Morgoth isn't just an Elvish version of Satan, he's Satan himself as the Elves understood him - with the implication that Satan is just the same being, viewed through the Abrahamic tradition.

I always thought tom is the embodiment of nature itself. Basically if nature was a man.

Yes.

My opinion: mostly obnoxious and good he was left out of the movie.

When I read about him, the first thing that came to mind is the concept of the "original man" from Manichaeism. However, the Lord of the Rings, being a trilogy that owes itself to Catholicism, would rule anything relating to Manichaeism out as a correct interpretation.

https://mastodon.social/@jolkienrolkienrolkeintolkein/110715400877074132

He's a character in the best story ever written...

My Immortal!

The most boring part of the book…in my opinion.