Anarrator who makes contradictory statements or voices doubts about his or her ability to retell a story well can be considered

Unreliable

Explanation:

A narrator that behaves in this way would be considered unreliable. An unreliable narrator is one that behaves in a way that does not appear to be trustworthy or accurate. An unreliable narrator will often contradict himself. He might also give information that the reader knows to be false. This can happen on purpose (the narrator wants to lie) or by accident (the narrator does not know reality well).

reasoning from several particular examples to establish a general principle