How do I handle the fear that my decisions could harm people?

The rules you write ripple out into lives in ways you cannot fully see, and the thought that you might cause harm you never intended frightens you. That fear is heavy, but it is also a sign of conscience. Someone who felt nothing writing rules that shape lives would be far more dangerous than you are. You cannot foresee everything; no one can. Demanding certainty from yourself before you act would just leave you frozen, and frozen is its own kind of harm. What you can do is your honest best with the knowledge you have, stay humble about what you cannot see, and be willing to fix what turns out wrong. A rule made carefully and corrected honestly is the most anyone can offer. Let that shape a practice: build in a way to listen for the harm you did not predict, and a willingness to change course when you find it. Responsibility is not perfect foresight. It is care going in and honesty coming out. Do your best, watch for what you missed, and correct it when you see it. That is not failure. That is doing the job the right way.