Ok, now that I’ve argued for the “invention of invention” as well as the the prime engines of engineering….
… I will next say written language because it crossed the barrier of death.
After all, how else can the dead speak long after their systems cease functioning? Verbal transmission is fine, but messages can change. Cultural transmission is sometimes even better as it’s the embodiment of concepts in living form.
But civilizations rise and fall…. So what remains?