First, assuming that by law we mean laws made by humans to govern human activities:
"How does a law rule without a human to interpret and/or execute it?"
A law doesn't rule, people enforcing a law rule. Laws are simply sets of enumerated restrictions with penalties attached, and "breaking" a law means that the society you are in has agreed that you will suffer a penalty for your actions.
That might sound like a narrow definition, but it is really quite expansive in application. For instance, we have laws that restrict people's ability to freely kill or steal, and if they do those things we impose a penalty (incarceration or death). But take any kind of law. Break a parking law and you are subject to a fine. Break a contract law and it is the same. Break a moral law and (some believe) you will be punished in the afterlife. So we have a series of restrictions with penalties attached.
Note: I think restrictions are a good thing. We do not want everyone to be free to kill whenever they like. But call a spade a spade. I'm also a lawyer, so this whole topic is close to home

But for a law to be effective, penalties must actually be followed through. For a short time, the threat of a penalty will keep people following laws even if there is no penalty... for just as long as people still believe there is a penalty attached. But if city governments stopped issuing parking tickets, after a while no one would follow parking signs. A "law" that isn't enforced isn't really a law at all, it is just something that looks like a law, it is law-ish.
A UN resolution is another good example. They look a lot like laws. They have code sections and are ratified and have most of the trappings of a law. But they have no enforcement. With no penalty, nations break UN "laws" whenever it is convenient. The only time a UN resolution is effective is when it is attached to economic sanctions or the deployment of troops.
Going back to the original question, humans don't "execute" laws, they enforce the penalties. If no one enforces the penalty, the law doesn't exist. It goes from being a restriction on activity to... a suggestion. A monologue on suggested restrictions or courses of action. But because it doesn't actually restrict activity, it is not really a true law.