[Bombadil]

Ah yes Kransha, I see you possess a great knowledge of what happenned to the ring. But your story ends too soon. You see the finger then crawled to the Old Forest and became Tom Bombadil. Mystery solved! When Tom refers to being around before the dark lord came from the outside he simply forgot about his former lord Melkor, noting Sauron as the only dark lord. Thus Sauron must've come into Arda hands first.

Now, this is why when Tom puts on the ring he is not affected, for it's old news to him. He had worn the thing for years before, and never went invisible either may I note. So there you have it: Tom Bombadil is not a Maia, Vala, Eru, a forest spirit, nor an enigma. It's simple- he is the finger of Sauron.