Based on the events in the first six chapters, it is possible that the cupboards have a magical origin and were created by ancient craftsmen or wizards. The cupboards seem to be connected to a world of magic and mystery, where different creatures and powers exist. The cupboards appear to be portals or gateways to this magical world, which is why they have the power to transport objects and people from one place to another.
It is possible that the cupboards were created to serve a specific purpose, such as to protect valuable artifacts or to provide a means of travel between different worlds. The fact that there are so many cupboards, each with its own unique properties and abilities, suggests that they were created by skilled craftsmen or wizards who had a deep understanding of magic and its workings.
The characters in the book, such as Henry and his family, are drawn into the mystery of the cupboards and their magical powers. They discover that the cupboards are not just objects of curiosity but can also be dangerous and unpredictable. As the story unfolds, it is likely that the characters will uncover more about the origin and purpose of the cupboards and their connection to the world of magic and mystery.