Man is dependent on natural law, but natural law is independent of anything man does, and exists whether man is around or not.
Exactly. And that's why it is not subject to change by men making up new laws. It's like trying to define "Pi" by statute.
Blackstone agrees, but the part of natural law that operates in the jungle, among animals, birds, and insects, has no application in deciding issues that arise among people and groups of people.
Blackstone says there is a body of natural law that applies to human interaction. Unfortunately, it is up to humans to discover this law. He cites three principles, live honestly, hurt nobody, render to every one it's due.