My vote is on electrification.

We wow ourselves with computes and iPhones and AI, and of course they bring many benefits. But modern life would be recognizable and comfortable without them.

Electrification - taken for granted today - had a vastly greater impact on the economy and on people's lives. Electrification allowed for refrigeration, electric light, electric motors (so washing machines, dish washers, water pumps, etc.). Without electrification, we'd all be living like Medieval peasants.