The two statements about first-person narration that are generally true are:
The narrator can be a witness or a reteller of events.
The narrator is a character in the story.
A narrator speaking in first person tends to witness some events in the story and can also retell the story to another character. Moreover, the fact that the narrator is narrating in the first person proves that he is a character in the story.
In first-person narration, the speaker talks using pronouns such as "I" or "We.