Is it a law of nature that people need air to breathe? How about water to drink? Or food to eat? Look at the Declaration of Independence for the United States:...
...And we see a piece of written enactment, a statute, not common law by definition. You tried. You need to understand "common law" doesn't mean what you think it means, and it is based on people creating it, it just isn't/wasn't formally written. What you should learn is the concept "natural law" is not the same as common law.