Unreliable
Part of speech: adjective
Definition: Not reliable.
Example sentence: I write unreliable narrators because - paradoxically - they're the most honest, true-to-life kind there is.
Fallible
Part of speech: adjective
Definition: Capable of making mistakes or being wrong.
Example sentence: It is true that from a behavioral economics perspective we are fallible, easily confused, not that smart, and often irrational. We are more like Homer Simpson than Superman. So from this perspective it is rather depressing. But at the same time there is also a silver lining. There are free lunches!