Yes, Steven, as suggested in the OP, there are all sorts of arcs / non-arcs.
But also as noted in the OP, the arc where a Protagonist begins in a state of Disunity and moves toward a state of Unity is the most common…
Yes, Steven, as suggested in the OP, there are all sorts of arcs / non-arcs. As writers, we should feel free to explore any and all of them.
But also as noted in the OP, the arc where a Protagonist begins in a state of Disunity and moves toward a state of Unity is the most common narrative archetype. Hollywood loves happy endings. A character who goes through a positive psychological change dovetails right into that type of ending.