There is no 'most important' human technology. All of it interlocks, and usually the prerequisite steps all need to be followed before you can progress to the next level. I wonder how long it would take given a paper copy of wikipedia (hopefully printed on acid free paper) to get back to a functional technology society. I'm sure it would go faster than the first time around, but I'm not so sure it would be less than a few hundred years.

Wikipedia is useless for rebooting technological society, it doesn't show where or how to mine the necessary minerals.