Time travel, I sold jars in the Qin Dynasty
An engineer of the basic structure of modern society traveled back to the beginning of Qin's unification of the six kingdoms (about 220 BC) and opened a grocery store. There is only one core product in the store - "Qiyao Can". Each person is limited to purchasing one item every seven days. The jar can theoretically contain any item from any era, but the probability is extremely low.
This is not an "invincible protagonist" story. This is the story of a person who relied on a modern cognitive framework and ideological system to understand, utilize, and spread things from the future, and ultimately profoundly changed the course of history.
The protagonist's advantage has never been "knowing more than others" - when he was sent to build the Great Wall, what could he do in the face of a group of craftsmen who had no measuring tools or engineering drawings? What can he do when the baggage train is lost deep in the Gobi and food is about to run out? His real golden fingers are: modern people's cognitive structure, systematic thinking, and underlying understanding of management and game theory. The jar is just a prop, he is the one who changes the world.
