I empathize with you. Literal-mindedness has been my own detriment for far too long, and my old forum and Story Page posts are testimony to that.

If that voice is meant to be a poetic description of the Arbiter's role/existence, it doesn't literally exist as a "character" within the Halo universe any more than the rest of the music does. I was so invested in the idea of uncovering a grand mystery back then that it never occurred to me that the better fitting answer would be simpler and less grandiose (Occam's Razor).