Who was the first person to kill someone? Why did they do it? Who was to say it was wrong if it was never done before?

I'm thinking about a self “shrink” system or application

There are so many things a good laugh heals, and it’s important for people to exercise this freedom as much as possible. Life is too short to be serious all the time, and those who focus on having the last laugh usually don’t laugh nearly as much as those who laugh first.