fire/cooking. this literally changed everything.
strategical thinking/the art of war. ants are the most warlike species on this planet, but they eradicate. there is no mercy. they take over and kill or chase out all the other species. they take all their shit. it doesn't matter how many drones die, all for the swarm. there will be no negotiations. humans, on the other hand, had to employ strategy.
smallpox eradication. this is probably the greatest single most enduring achievement that was purposefully done by the human race to date because it was done by us for us now and for our children forever, regaless of sex or creed or genetic code... humans saved them all from having to endure it
nuclear fission. nature doesn't even do it, but we do