What does it mean for a canon to be "widely accepted" when we're talking about fragmentary historical documents? Believed by the most people (how would we know)

What does it mean for a canon to be "widely accepted" when we're talking about fragmentary historical documents? Believed by the most people (how would we know)? Discovered first (an accident of archaeology)? Part of the literary chain that leads to the stories we tell in modern times (but which "we")? I think this concept is less simple than one might want.