What is the moral to The Canon's Yeoman's Prologue and Tale

The Yeoman tells us quite plainly that the moral of his story is that things are not always what they seem. ... The moral also generally refers to the Canon and the Yeoman themselves who might have seemed like trustworthy characters when they first approached the pilgrimage, but appear less so as their story is told.

Explain:

When its asking for the moral of the story, its basically like the big idea like what its all about.

v

so is this a rhetorical question?