This story leaves the reader with questions because the author is purposely ambiguous in the symbolism and meaning of the story. The reader is left to decide for herself what she thinks all of this means. Since this is an allegory, we should be able to take some meaning and lesson from the story, however. To me, the old man symbolizes man's reaction to what he cannot or does not understand. Man has preconceived ideas about certain things, and the old man as an angel doesn't fit our notion of what angels should be. He is dirty and old, not majestic, certainly not fitting as an angel of God. He doesn't speak to the humans, and they are repulsed by him. The humans cannot explain the old man, so he is discarded.
The spider-woman appeals to the humans because she can explain how she became a spider-woman, teaching them a moral about children obeying their parents. The humans feel sorry about her sad story. The spider-woman's magical transformation is explainable and is something we might find in a fairy tale. The humans can accept that.