What are the main two themes that comes out of this text?
One clear theme in "A Very Old Man with Enormous Wings" is the contrast between the natural and the supernatural. The old man is himself the best example of this. He is clearly human, yet he has wings (wings that are so natural it's a wonder everyone doesn't have them, says the doctor) and can fly. He's treated like an animal, which is even worse, but it's clear the people think he just might be an angel. The priest is convinced he's human based on his outrageous tests of his humanity, yet he, too, treats the old man poorly. What to believe and what to believe about the old man, among other things, is one of the clear themes of the story.
Another theme is the fickleness of humans and their faith. Here comes an oddity which attracts a lot of attention, a very old man with enormous wings. People stand in lines for hours just to see him or touch him, hoping he can somehow heal their odd ailments. When the next thing comes along, the half woman-half spider, they jump to that. There is no real spiritual overtone to her story or her person, but the crowd shifts its allegiance to her. Their faith is fickle, as is their attention span. The story ends, but we know without a doubt the crowd would move en masse to the next thing as soon as it appears.
There are other themes, of course, and I've included a link to several helpful enotes sites below.