I believe you're referring to the short story "A Very Old Man with Enormous Wings" by Gabriel Garcia Marquez.

The subtitle "A Tale for Children" is appropriate for a number of reasons. First and foremost, the story contains more than a few elements of magical realism, to which children respond more naturally than adults. The idea of a very old man with enormous wings suddenly showing up in a remote village might seem (to adults, at any rate) a little far-fetched. But not for children, especially those reared on fairy tales.

One could also take the subtitle in an ironic sense. There's a fair amount of satire on display in the story concerning the religious beliefs of the common people as well as the role of the Catholic Church. Perhaps Marquez wants to suggest that there's something rather childish about the credulity of some of the locals in ascribing angelic status to the old man.

Then again, one could also argue that Marquez, in subtitling his story this way, is seeking to draw attention to the childlike wonder that should be inspired by the sudden appearance of the old man, but which has been cynically occluded by the desire of some of the locals to make money out of his alleged miracle-working powers.

Any one of these interpretations is perfectly plausible. The fact that there's no one answer to this question simply reminds us of the richness and complexity of this remarkable short story.