What made man start giving death penalties?

Well everything is inspired by something so back in old times, embarrassing people(not like public, it means like force them to have intercourse with u), bloodshed, or cheating on your spouse will result in the death penalty because it was so serious and they didn't have those iron stone prison buildings we have today so maybe death was easier than serving time, but death penalties were given because of religion, crazy religion like devil worshippers, baal, and etc, people were cutting themselves to death/sacrificing children or themselves to death as well. Today we don't do death penalties, we just serve time, terrroists do death penalties but that is not right, what made man start, that's unknown but it did happen and it became popular in states.