It's tough to know absolutely everything about a complex dynamic system, even if it's built by humans. Take the economy, for instance. Invented by humans, made up of humans and human technologies and concepts, and yet people only have vague ideas about how to control it.

Or take computers for that matter. People designed and built them from scratch. Someone had to design and lay out the transistors on the CPU, and presumably they know everything about how to do that. And yet we are currently trying to figure whether there's an ordering to switching the transistors on and off that would imbue the CPU with human-level intelligence. There are plenty of people who know computers inside and out, yet there are still questions that need answers. We have a whole discipline called Computer Science that performs experiments on computers for the purpose of answering these questions.