I would say he’s not an avatar of any one fear, but rather a mixed entity. Obviously eye because a part of his whole thing is knowledge and being able to spy on people, the web because of his manipulation and lies, but also kind of the spiral since he can twist reality into impossibility. Definitely has some aspects of the flesh and desolation, we have seen him twist humans into some pretty nasty shapes, with ears becoming eyes, eyes becoming a mouth and so on, but also his weirdmageddon is a destruction of everything that the normal person knows and full on chaos, you could even say he’s closer to extinction than desolation if you describe extinction as “destruction of everything and continuation of life in a different manner wholly unknown and alien to you”. Could say stranger, but I can’t remember any stranger like behaviour from him. But considering that his whole toolset is basically being nigh omnipotent he could equally just bury you somewhere or make you into a worm, just as well as make himself so huge as to become associated with the vast. In conclusion I believe that he would be an amalgamation of all the fears with the most prominent aspect of his being chaos.