Ironically, this example would be much better suited to an approach that simply makes him a PC with minimal abilities, and to have the DM contrive events external to him that allow his survival.
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LotR is about many things, but it is certainly not about Frodo making informed or efficacious decisions or being a "protagonist" in the sense you describe. Roleplaying that character would be best achieved by creating mechanics that make him clearly impotent and conveying a sense of helplessness on the player when confronted with obviously superior challenges.
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Tolkien is also the prime example of focusing on setting rather than plot or character and spends hundreds of pages running on about places and things that have nothing to do with the protagonists ("hidden backstory" in your lexicon) and is frankly the antithesis of most of what you think about rpgs. I assume you must have the same aversion for his work that you do for the gaming style that derives from it.