Lawful doesn’t mean right. Slavery was lawful.

Laws are not immutable. Slavery is an example of something that was lawful and then society added rules against it.

In US, the society didn't just "add rules against it". If you recall, the slavers first had to be beaten with a very big stick.

society literally had to break down for years in order for us to add rules against it

https://en.wikipedia.org/wiki/American_Civil_War

and your point is?

That we operate as a society within the confines of the law. And the confines we exist in can be changed if the majority don't agree that something isn't right.

Actually there are specific confines that cannot be changed by majority. Might I refer you to the US Constitution, which itself constrains which laws are flexible and which are not, and which this administration has run afoul of now on hundreds of occasions?