It does not describe "a series of errors that should not have been made" at all.
What it effectively says is that if we want to truly understand the cause of an accident, we have to examine the conditions and human factors that lead to or influenced the error/bad decision.
Lots of things come into play there i.e Goal focus, commercial pressure, fatigue, cognitive overload, communication problems, distraction at critical times, recallable knowledge, environment, familiarity etc etc.