I don't have enough information to determine the main characters. It could be an old man or woman who is the central figure, or it could be a group of older individuals.
Without more context, any speculation about the main characters is just that - speculation. However, it's possible that the main characters are those who have defied age in some way. They could be people who, in their later years, have found new purpose or have been forced to face challenges they thought they had left behind. For instance, it could be an aging athlete who decides to make a comeback and the prequel story details his early days, his setbacks, and how he got to the point where he is considering a comeback. Or it could be an old artist who rediscovers her passion and the prequel shows her life before she lost and then regained that passion.
I'm not sure specifically as it could be about various things. It might be a story about someone achieving their dreams at an older age, like an elderly person starting a new career or a new adventure that is related to a prequel of a certain event or series.
It might be a young protagonist in the prequel who constantly got into trouble and received spankings. As they grew older and the story progresses towards the 'never too old' part, they became wiser from those early experiences and became someone respected in their community, with their past spanking incidents being a part of their growth story.
The 'never too old prequel' might be about events that happened before a main story. Regarding the'spanking story' part, it could be a comical or moral - teaching plot. Maybe it's about an older character who, in their youth (in the prequel time), got spanked for misbehaving and learned an important lesson from it.
As of now, it's hard to say exactly who the main characters will be. But they will likely be members of noble houses or those with a connection to important events in Westeros' history.
Most likely, the parents of the family from 'A Christmas Story' would be main characters. Since it's a prequel, it would make sense to focus on them.
Wonder Woman herself is surely one of the main characters. There might also be some of her Amazonian sisters who play important roles in her backstory.
I don't know specifically, but there could be a brave protagonist.
There could be the predecessors of the Gamemakers. They would be important as they are the ones who design the Hunger Games.
There could be the predecessors of the characters from the main game. Maybe the early versions of Six or the other kids we see in the original 'Little Nightmares'.
I believe Rafiki could also be a main character. He's an important figure in the Lion King world. In the prequel, he might play a role in guiding the young lions or in the spiritual aspects of the Pride Lands. Maybe he knew secrets about the past that are relevant to the story.