The main character is surely the girl that was left behind. Depending on the nature of the story, there could be other important characters. If it's a story set in a community, there might be neighbors who play a role in her life after she was left. Or if it has a more romantic angle, there could be a new love interest who comes into her life later, helping her to move on from the person who left her.
Since I haven't read the novel, I can't say for sure. But I assume the girl who was left behind is one of the main characters. There might also be the people who left her, even if they don't appear much in the story, they could still be important as they are the cause of the girl's situation.
Since I haven't read it, I can't say for sure. But I assume the girl and the man who left her are the main characters.
Probably there is the girl who was left behind. And perhaps the person who left her, like a lover or a family member. There may also be other characters who come into contact with the painting related to the girl, such as art collectors or people who try to find out the story behind the painting.
I'm not sure as we don't have enough information. It could be ordinary people who find themselves in an extraordinary situation of being left behind.
In the 'left behind film story', there could be a family man who is left behind and has to take care of his family in the new, dangerous world. Another main character could be a journalist who is trying to uncover the truth about what has happened. And there might be a religious figure who helps guide the others through their spiritual journey during this trying time.
It depends on the specific game. In some cases, it could be a secondary character from the main game who becomes the focus in the DLC, like Ellie in 'The Last of Us: Left Behind'.
If it's a story about a sports team, the players are the main characters. They support each other during tough competitions. For instance, if a player gets injured during a game, the others might adjust their strategy to protect the injured one and make sure they all cross the finish line together, metaphorically speaking. This shows that no one on the team is left behind.
There could be a kind - hearted wizard or warrior in the story who takes it upon themselves to help the goblins. So they would be a main character. And of course, there would probably be some goblin characters, perhaps a young goblin who is in particular need of help and whose story becomes central to the 'no goblin left behind' concept.
As we don't know the details of the 'arrow left behind story', it's impossible to say who the main characters are.
I'm not sure specifically as I haven't read the 'left behind the novel'. But typically, in a novel with a title like that, there might be a character who is the one left behind. It could be a child, an adult, or even an animal in some cases.