a statement that makes an argument. It announces to your reader what you intend to prove about a particular story or character. If a thesis idea is not "jumping out" at you, then my recommendation is to go with a thesis that examines either characters or themes. Those two things will likely overlap as you support your argument about a character or a theme. For this story, I think a good thesis could focus on greed. Elisenda is a good character to use in support. It is her idea to start charging people to see the angel. She wants money because she desires stuff. She is an incredibly materialistic character.

Elisenda bought some satin pumps with high heels and many dresses of iridescent silk, the kind worn on Sunday by the most desirable women in those times. The chicken coop was the only thing that didn't receive any attention.

The quote also shows a bit of Elisenda's tendency to worry about how other people see her. It could be argued that there is nothing wrong with these traits, but Elisenda shows readers that these desires motivate her to use and abuse the people around her for personal gain. A possible thesis could be something like the following thesis.

"Although there is nothing wrong with desiring ownership of nice things, Elisenda shows readers how avarice can lead to the abuse of other people."

One good topic would be the loss of spiritual meaning in the lives of the townspeople. When they find out that there is a man who might be a literal angel -- a supernatural being that is a direct representative of God -- in their town, they do not respond spiritually, but with coarse amusement:

...the whole neighborhood in front of the chicken coop having fun with the angel, without the slightest reverence, tossing him things to eat through the openings in the wire as if weren't a supernatural creature but a circus animal.
(Márquez, "A Very Old Man with Enormous Wings," salvoblue.homestead.com)

This disinterest in experiencing the supernatural extends to those who travel to see the angel; most are there simply to stare, while some desire miracles and healing. The keepers of the angel, for their part, use it to make money instead of searching for personal spiritual meaning, and are relieved when the angel leaves. A good thesis statement on this topic might be: "As humankind continues into the Modern Age, his connection with spirituality diminishes." 

A most unusual story, "A Very Old Man with Enormous Wings" by Gabriel Garcia Marquez is classified as Magical Realism.  This term of two words is indicative of the central idea of Marquez's story.  For, it is a parody of the act of interpretative process as it treats two facets of this process:  logical explanation and invention/imagination.

To develop this thesis, here are some main points to consider in the search for supporting details:

• When the old man arrives, Pelayo attempts a logical interpretation, declaring that he is a castaway because he speaks with a "sailor's voice."  However, there is no real logical basis for Pelayo's reason, and it is rejected.  The next interpretation of the old man's appearance is made by a neighbor woman believed to know "everything about life and death."  Her humorously prophetic pronouncement that he is an angel also has no logical foundation.  Five other interpretations offer concrete explanations, but none are logical.  The old man is the mayor of the world, a five-star general, or the first of a race of winged wise men who will take charge of the universe. 
• When the priest, Father Gonzaga is called upon as the "official" interpreter for the village, he simply sends a letter to the pope, a letter that is never answered.  In the end, there is no explanation for the old man; instead, in their unimaginative way, Pelayo and his wife exploit the old man with wings and make an exhibition of him, charging admission.  When the Spider Woman arrives, the people prefer her since she is partly human and provides them an explanation they can comprehend.  Soon, the old man becomes uninteresting and he is relegated to the backyard, parodying the way that reasons are thrown out.
• Some interpretations of this story point to the angel's being imaginary, and because the people cannot utilize their magical/imaginative state, they fail to interpret the appearance of the angel.  They  refuse to understand that the magic of the imagination defies reason.  Lacking the imaginative, magical world from which he has come, the old man finally disappears as an "imaginary dot" on the horizon since there are magical events that occur that cannot be interpreted.  This imaginative process takes precedence over the logical as the reasons for the angel are, at best comical.  In addition, the reader becomes involved in the invention/imagination aspect of the story as he/she comes to understand that often the irrational is a natural part of life and, as such, must be accepted.