[Certhas]

Not the person you are asking, but... In my view, the two most important technology clusters in human history are writing and industrialization. The former made culture (cognitive work) cumulative. The latter made physical work approximately free, with the result that we now have 5% instead of 95% working on producing food. Now we have a technology that could potentially be a culmination of these two: The industrialization of cognitive work/culture.

It isn't absurd to think this is one of the most consequential technologies ever. It probably doesn't make sense to rank technologies (which build on top of each other after all) by importance, but it's fairly clear this is a historic breakthrough.

[jerojero]

Agriculture is the most important set of techniques and technologies in human history, it gave us the possibility of staying in a place.

There's also fire.

Writing was very important, I'm not so sure about industrialization, maybe as modern men we might think that way. But human life was perfectly liveable and conceivable without it. Even writing. Big civilizations like the Inca empire didn't really have writing (although they had the quipu system for record keeping).

If there's a civilization collapse, we will still be doing fire and agriculture. We probably won't be doing industrialization and computers.

[Certhas]

Fire predates modern humans. I will concede agriculture as up there with the two I mentioned, but I think you underestimate how radical the shift of industrialisation was/is, and I think this is because history teaches us about highly atypical lives from the past. City dwellers, kings, etc...

In fact you could reasonably argue that life for most people didn't change that much from establishing agricultural settlements all the way up to industrialization. Most people spent most of their time procuring food and clothing/shelter using roughly similar methods.