Since I have no knowledge of 'the train short story', the main characters could be various. It could be a young adventurer who decides to take the train to an unknown destination, and on the way, meets an old wise person who imparts some life - changing wisdom. There might also be a group of friends who are having a reunion on the train, and their interactions and conversations form the core of the story.
As I don't know the particular 'on the train short story', I can't say for sure who the main characters are. It could be a lone traveler, a group of friends, or a family.
The main character is surely the girl on the train. There may also be other passengers or train staff that could be considered important characters depending on the story.
Not having read 'the man on the train short story', it's difficult to determine the main characters precisely. The man on the train is surely a central figure. There could be a mysterious stranger sitting next to him, who is also a main character and whose actions or words drive the plot forward. Additionally, there might be a family on the train that the man interacts with, and they play an important role in the story as well.
The main character is a father who is traveling with his daughter. There are also other passengers on the train who play important roles in the story as they all face the zombie threat together.
I'm not sure as I haven't read the story, but it could be a young adventurer who stumbles upon the ghost train. Maybe there's also an old railway worker who has heard tales of the train but never believed them until now.
I don't know as I haven't read it. Maybe there's a tired traveler who is desperate to get on the last train. There could also be a train conductor who plays an important role in the story.
The main character is a man who stumbles upon the mystery of the midnight meat train. There may be other characters like the train conductor who has a rather menacing presence in the story.
Since the 'train story' isn't described, the main characters could be a detective who is on the train to solve a case. Or it could be a family traveling together. There might also be a hobo who lives on the train.
There could be a commuter, someone who travels by train regularly for work or school. Maybe a traveler who is on a new adventure. There might also be a station attendant.
In the 'free train story', the main characters might include a family that is given the opportunity of a free train journey. There could also be a railway official who decides to make the train free for some reason. And perhaps there is a stowaway who sneaks onto the free train and becomes part of the story.