Joshua Kronengold

Arwen is extremely important at the ending -- she's the last surviving named character in Middle Earth.

Sam -is- the other one who stays for a long while, then goes. Those two are Frodo and Sam.

Merry, Pippin, and various others aren't really part of this, because they belong in middle earth, and they stay in middle earth; I'm not talking about the Fellowship, but those on the boundaries. Or I'd have mentioned Gimli as well.

So the elves, Gandalf, etc go to the west. So, eventually, do Frodo and Sam. Aragorn and Arwen might go to the west as well, should they choose; Arwen's half-elven and can choose to go either way, and Aragorn could arguably have made that choice as well, both through mercy (because of his true love with Arwen) and genealogy (Aragorn is, after all, of Elven stock himself, the first Numenorian king having been Elrond half-elven's brother -- though it seems that while descendants of half-elves who choose immortality might make their own choice and become mortal, that descendants of those who choose mortality do not have the choice presented again at every generation. Perhaps because the blessing of man (i.e., that of free will, or if you like, free destiny) is deemed so much greater than that of elves (immortality)? Hell if I know.

Regardless, yeah, if I were considering the -fellowship-, it would have been more like "one dies, four rise to greatness, three depart, and two write a book". (with Sam appearing three times, and Frodo twice, and leaving out G's death and return as not an -ending-, exactly).