After looking into your oblique reference to "Campbell," I see that you are actually referencing a specific type of "Hero's Journey." That's a particular definition with specific points.
Campbell's definition (as given on the Wikipedia page) is rather specific to fantasy and mythology, and is a rather specific formula that tries to be an all encompassing description of the content of myths and fantasy. It isn't a blueprint for writing a story so much as a distillation into one plot line of common elements across all of mythology and fantasy.
If you try to follow it as a blueprint, you'll go nuts.
It's not telling you how to write a story, it is telling you of all the things a story may be composed of.
You don't want to follow it to the letter. That'd be like ordering a pizza with everything on it - you'll choke trying to eat it.
Campbell's definition is saying that existing mythology is composed of elements from that huge list - and that if you write fantasy or myths then your story will contain elements from that huge list.
Keep in mind that the "Hero's Journey" doesn't have to be heroic.
The title "Hero's Journey" is one of many ways to say that your character grows or overcomes obstacles.
A short summary of the "Hero's Journey" plot is like this:
- Introduce character
- Character encounters problem
- Character struggles
- Character overcomes problem
- Character learns or improves for having struggled and won
- End of arc
That looks like the plot of pretty much any story or story arc.
What makes the "Hero's Journey" that most people think of is that the problem is enormous, the struggle titanic, and the character heroic. The "Hero's Journey" is really just a big name for a mundane thing.
Any obstacle the character meets is a "Hero's Journey" in small format.
Even if the character doesn't win (overcome) the problem, then it is still a "Hero's Journey" as long as the character grows or improves because of the struggle.
If your character(s) confront the obstacles they face and win (or at least learn from the struggle) then you've ticked the "Hero's Journey" box on your checklist - if you feel the need to use a checklist and do all the things people will tell you that you must do to write a good story.
A good story starts with a point to make. You as the author must have something to express. A story or novel without that goal is a series of pointless anecdotes.
If that goal isn't there then I, as a reader, will wonder why you bothered to write the story at all and why I should bother to read it.
Your characters don't have to know what the point is, but you as author must know. Without that, your story will wander aimlessly and you'll have trouble deciding what to do from scene to scene.
If you (as the author) have a point to make or a goal to achieve, then you can see how to warp your story and characters as you go along.