"I see your point. And of course it _is_ literary. He's not in fact trying to reproduce the cadences or diction of informal speech. For one thing the characters with whom he's dealing at this point are not characters who would have spoken in a demotic register. But also, and more interesting to me anyway, is how he _suggests_ an actual human voice through the medium of highly literary language."
I agree. I think Conrad's gift was precisely this suggestion of a human voice, and not just any voice, but an introspective, reflective kind of voice. The kind of voice the readers themselves would be wanting to internalize, to be held by.
The notion that storytelling is simple and free from ornament or literariness is shaped by an age that has lost its storytellers. I grew up in a country where most social entertainment still consisted of story telling, and what I observed is that there was a great delight in language, ornate expression, made-up words (stuff we'd normally call literary).
The (20th century) middle class vision of the working class has given us this bare knuckled hero with few words to spare. This is a stylistic trick that can serve to indicate energy dammed, words withheld, suffering muted....but it is not representative of actual habits of speech and narrative which, from what I have noticed, exult in embroidery, rhythms, flights of fancy, and the sheer luxury of words. You can see this in a lot of hip hop lyrics.
j.