It can be argued that "Lost" doesn't really have a central main character. After all, each episode of the series frames its narrative around a different specific character, allowing for the show to cycle through a range of individual viewpoints. However, if there is one character the series returns to again and again and focuses on the most, that character would obviously be Jack. Not only does the show open and close with episodes built around his perspective, but Jack also appears in the more "Lost" episodes than any other character.
Out of the 119 episodes that make up "Lost," Jack appears in 113 of them, sometimes in a minor role, but more often than not having a prominent presence on screen. Jack also has the largest number of episodes focused on him specifically, with a total of 12 "Lost" episodes being "Jack-centric," meaning Jack is the focus on the episode's flashbacks, flash-forwards, or flash-sideways.
Additionally, Jack encounters more characters than anyone else on "Lost," making him a link connecting individuals impacted by the events of the story. That's true to a lesser degree for many other characters, however nobody on "Lost" meets more major or supporting characters than Jack. For instance, Sun and Sayid never meet Dr. Chang, Hurley never meets Eloise, and Sawyer never meets Illana, but Jack meets all of those folks at some point.
