Thus, there is no MC development in the story. It's starting to get boring now.
I think it's established that there is no character development for Cid because he's an all-powerful chuunibyou that wants to be this unstoppable force to show off his powerful chuuni moments and make an illusion that the plot is moving forward (hence why there's so much "It's time." lines). He acts like a force of nature that is "relevant" to the plot that happening around.
If you're expecting character development, Claire, Alexia, Rose, (Sherry for one arc) and Alpha are the true MC that the plot revolves around their arcs. If you can ignore Cid's perspective in every arc, you can see through their perspective that a powerful dark organization, the Cult of Diablos were the behind of the events that happened in their lifes thus they need to find a way to learn more about this secret society and put an end in their reign once and for all. Cid's relevancy to their arcs is in 2 way; Cid's mob form appear like a recurring side character, sometimes help them in their arcs, sometimes served as their motivation. On the other way when he's Shadow, appear as a tritagonist (side protagonist for Alpha), neither a help or hinder to them but somehow involved in opposing the Cult of Diablos, while for Sherry, an antagonist and possibly her motivation in a later plot.