"human history" covers a lot of territory. in terms of fundamental changes, nothing comes close to agriculture (let population densities skyrocket, enabled pyramid-style social setups) and writing (let knowledge accumulate rapidly from generation to generation).
Not to mention the wheel (that ubiquitous cliche), the discovery of bronze (an alloy of copper and tin that allowed for more durable weaponry), the Haber-Bosch process; and so on.
