A small advance occurred when polytheism yielded to monotheism because many false gods were dismissed as fictions.
However, the new fiction of “the one true god” was born, and with that much mindless strife that locked the world in blind faith and senseless violence.
With the birth or rebirth of skepticism, the big advance occurred. Belief in no gods was the big advance because none of the religions that preach a version of the one true god is supported by evidence, and all such belief systems are contradicted by evidence.
With the birth of skepticism and science, there was no more blind faith – by definition, a scientist is a skeptic, very slow to believe anything; a scientist believes in propositions only to the degree that they are supported by credible evidence, and provided that no credible evidence says they are wrong. That is a major advance. Generate high quality scientific data and model it ever more accurately and precisely. Don’t waste time defending the details of models that do not fit the data in detail.
Adoption of a sensible secular humanism to replace religions would be another advance. Unification of the entire world under one flag would be another. Unification of the entire universe of intelligent beings would be still bigger. And bigger than that…