While the title suggests this is a simple story for children, "A Very Old Man with Enormous Wings: A Tale For Children," by Gabriel Garcis Marquez, is much more than that. The "captive angel" to which you refer may or may not actually be an angel, but he is certainly a captive and a curiosity, both of which are true only because of Pelayo and Elisenda.
Pelayo discovers the odd man-creature and immediately tells Elisenda, his wife, what he has found. Though neither of them really understands the being that landed in their courtyard, they do seem to understand that he will be as curious a spectacle to others as he is to them. Elisenda decides relatively quickly to capitalize on the strange angel-like man, and they make the old, winged man the center of a kind of freak show.
They treat the old man abominably. At first they "dragged him out of the mud and locked him up with the hens in the wire chicken coop." Because they think he may have been responsible for a miracle (their child's fever goes away), the next morning
they felt magnanimous and decided to put the angel on a raft with fresh water and provisions for three days and leave him to his fate on the high seas.
Instead they see that their neighbors are gathered around the angel's cage, treating him disrespectfully and throwing food at him. Later they will allow the old man to be even more severely abused. Nothing about this situation seems to impact the couple except the potential for profit; so they, like their neighbors, treat him "as if weren't a supernatural creature but a circus animal" and charge admission for people to see him--and a lot of people come to see him.
Using this poor old man as a means to their greedy ends, Pelayo and Elisenda soon grow quite rich.
With the money they saved they built a two-story mansion with balconies and gardens and high netting so that crabs wouldn't get in during the winter, and with iron bars on the windows so that angels wouldn't get in. Pelayo also set up a rabbit warren close to town and have up his job as a bailiff for good, and 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.
Everyone benefits from the creature's miserable existence except the poor man himself. They build a new house, considered a mansion in this village, specifically designed to keep him--nothing else--out, and they do everything to improve their living conditions but completely ignore the old man in the chicken coop.
The "very old man with enormous wings" never says a word to them, but Elisenda routinely yells at him and scolds him. Pelayo is as much to blame for allowing such treatment to continue. The supposed angel has given them health (they superstitiously believe) and the ability to live a life of leisure, free from any money worries; in exchange they give the old man nothing but disrespect and anger.
When the angel-creature finally leaves, Elisenda is working in the kitchen of her mansion; all she feels is relief "because then he was no longer an annoyance in her life." The couple is ungrateful and greedy, using the unfortunate creature to advance their own causes without ever giving him anything in return, including common decency or respect.