If 'Star Trek The Real Story' is about the making of the series, the main characters could be the actors like William Shatner (Captain Kirk) and Leonard Nimoy (Spock). Also, the creators Gene Roddenberry would be a main character as he was the visionary behind the whole 'Star Trek' universe.
It could be argued that the fans are also main characters in 'Star Trek The Real Story'. After all, it was the fans' love and support that kept the franchise alive over the years. They have been part of the real story by creating fan - made content, attending conventions, and spreading the word about 'Star Trek'. And of course, the core characters from the show like Captain Picard from 'The Next Generation' are also part of this real story as their story arcs and development are part of what makes 'Star Trek' so special.
Well, in a sense, if it's about the story behind the story, the main characters would not only be the on - screen actors but also the writers, producers, and directors. For example, Gene Roddenberry who had this grand vision of a future universe. The actors who brought those characters to life were also crucial. People like DeForest Kelley as Dr. McCoy added so much to the real 'Star Trek' story through their performances and the relationships they created on set.