A'most ambitious experiment' in a short story could imply that the experiment is on a grand scale. It might be an experiment in a social or psychological realm, such as an attempt to change an entire community's way of thinking. The short story would then explore the consequences, both expected and unexpected, of this very ambitious undertaking.
I'm sorry, I don't know the 'A Most Ambitious Experiment' short story well enough to say who the main characters are. They could be scientists if it's a scientific experiment - type story, or they might be ordinary people who get caught up in the experiment.
I haven't read the 'A Most Ambitious Experiment' short story specifically, so I can't analyze its plot directly. But generally, in a short story with such a title, the plot might revolve around a scientific or social experiment that is highly ambitious. There could be characters involved who are either driving the experiment forward or being affected by it. Maybe there are unforeseen consequences or challenges that they face during the experiment.
A compelling story would have a unique and risky experiment idea. It should also have characters that are deeply involved and whose lives are changed by the outcome.
I'm not sure specifically as you haven't given more details about it. It could be about a scientific experiment, a social experiment, or something else entirely.
The main characters are the ambitious guest, of course. And then there is the family that he encounters. There is the father, the mother, and the children in the family.
The main themes in 'the ambitious guest short story' include the concept of fate. The actions of the characters seem to be influenced by some sort of unseen force, which could be related to fate. Additionally, the theme of human aspiration is there. The ambitious guest represents the human desire to achieve something greater, to reach for the stars so to speak, and this theme is explored through his character and his interactions with the family in the story.