The laws that were both actually enforced and reasonable basically were. I don't think we need to emulate things people historically said they would do even though they didn't, or did do but were unreasonable.

That seems circular to me. Surely most people follow the laws that seem reasonable to them. If everyone agreed on what was reasonable behaviour, we wouldn't need laws.

Basically everybody knows that murder is wrong but some people still do it.

People do try and argue its justified in specific circumstances. Sometimes people have an over-active imagination for what constitutes self-defense.

Hell, trump pardoned someone convicted of murder (which is disgusting, but i guess he thought it was reasonable).

But my main point is there was never a time or society where the only crime was murder.