From the writing point of view, Frodo is a character that makes sense. He's a hobbit, he isn't some stock bland MMORPG/Skyrim type warrior. He carries the ring, the ring corrupts men, yet he has to carry it because it affects him (as a hobbit) at a slower rate. From a written character point of view, the hobbits serve as viewer's guide to the world they inhabit. Meaning, the hobbits don't know much of the outside world they live in, same as the reader, so they're a good tool to use in the storytelling- if something gets explained to the hobbits it's really being explained to the reader. Even their location on the map serves to explore the entire world. Just look at where The Shire is compared to where Mordor is: http://lotrproject.com/map/ But back to his character. Frodo is carrying a burden. It's a draining burden, like https://en.wikipedia.org/wiki/Albatross_(metaphor) Frodo knows he's no warrior, that he doesn't belong outside The Shire, yet still carries on.