Coco is a great protagonist for Witch Hat Atelier. It is obviously a good idea to have a main character that is as new to the world of magic, as the audience.
But besides giving opportunities to have "how the magic works" explained to us, she also has the ability to look at this well establishes, outright ossified system with fresh eyes in world. Very important for a show that wants to explore changing the status quo of its unfair magical world.
She is also interesting because she has this terrible guilt and fear of being inadequate/of failing. Nevertheless she is kind and mature when dealing with other people. And she is quite smart and creative with the magic, to offset her low amount of practice related ability.
