Are rules, laws and morals ever or have they ever been "set in stone"?

Literally the Ten Commandments.

Well, no, rules, laws and morality are obviously not immutable. (They have been literally written on stone, though. But being written on stone hasn't stopped them from falling into obsolescence).

We change rules and laws all the time. That's one of the functions of government.

Theories of morality generally evolve more steadily, but they certainly change over time.

There are some prohibitions that appear to have been with us since the dawn of civilisation and are pretty much fundamental to civilisation. For example, societies have pretty much universally had penalties for murder and theft since before 2,000 years BC. The Code of Ur-Nammu, the Code of Hammurabi, the Mosaic code, &c. There's even a possibility these moral prohibitions are partly instinctual. They almost certainly have prehistoric roots. They certainly weren't handed down to Moses on a mountaintop; they definitely predate that myth.

Even though a lot of people in the modern world still seem to worship the god of an iron age tribe (or pretend to), almost none of them actually follow all of the rules, laws and morality inspired by that god. So, yeah, things do change even among people who imagine themselves to be following the immutable and perfect 'word of god' in scripture.

October 3, 2021 Sunday 8:35 PM ET
*Update: Oct. 3, 2021 Sun. 9:00 PM ET

Anything from the civil codes (conditional) are subject to change because they are based on a subset of rules dependent solely on cultural attitudes, mores, customs, and social outcomes. They are suited to directly meet the needs of the people.

The moral law however remains fixed, meaning it does not change because it is derived from teachings (tradition) established by consensus (natural law as part of it too). These are (unconditional) principles such as love, forgiveness, kindness, compassion, integrity, humility, contact, honesty, mercy, justice, dignity, *self-control, and patience on which all of humanity and civilization rests.

They are self-evident invisible values made visible through deed or action. Being timeless, there's no need to amend the message; only in order that it may be clearly understood without miscommunication or confusion (the reason of its recording and keeping in the first place).

~~/o/

The details of laws and rules change over time, but the basics are pretty much the same through most times and places: Don't steal, don't damage other people's property, don't hurt the interests of the community as a whole, don't kill unless it's considered your civic duty to do so, don't have sex with close relatives, etc.

The details vary per time and place, but that doesn't mean it's okay to break the law concerning those variable details. Wherever you are, you're subject to the local laws.