Since I haven't read the 'Harvey's Dream' short story, it's difficult to say for sure who the characters are. However, based on the title, Harvey is the central character. There might be other characters that are part of Harvey's dream world. These could be people from his past, present, or even imaginary figures. Maybe there's a mentor - like figure in his dream who guides him, or an antagonist who creates conflict in the dream scenario.
I don't know as I haven't read it, but likely Harvey is a main character. There could also be characters who appear in his dream, like friends, family members, or perhaps even strangers who play important roles in the development of the dream and the overall story.
Not having read the 'Read Harvey's Dream short story', I can only guess. Harvey is obviously a key character. There could be secondary characters that are either manifestations of his subconscious or real - life people who have an impact on his dream. For instance, if the dream is related to his work, there could be colleagues or a boss in the dream. Or if it's about his personal life, his romantic partner or family members might show up. These characters would interact with Harvey and contribute to the plot and themes of the story within the dream context.