Which narrative voice knows the thoughts of all characters without using 'I'?

The narrative voice that knows the thoughts of all characters without using "I" is third person omniscient. In this point of view, the narrator has an all-knowing perspective and can access the internal thoughts, feelings, and motivations of every character in the story. This allows for a more comprehensive understanding of the narrative, as readers can gain insights into multiple characters simultaneously.

In contrast, the first person narrative is characterized by the use of "I," where the narrator shares their own personal experiences and perspective, limiting the insight gained to that single character. The second person narrative addresses the reader directly using "you," which creates a different kind of intimacy but does not provide insight into characters' thoughts. Third person limited, while employing a third person perspective, only conveys the thoughts and feelings of one specific character, thus not offering the complete scope that the omniscient perspective does.