Traveling Through the Qin Dynasty, I Lived into the 21St Century

Picking something up in an antique shop, I touched a bronze sword and was accidentally sucked into it, traveling to the Qin Dynasty. The system only takes a bottle of elixir and enters standby mode. The side effect is: seeing all the people in the world of birth, old age, sickness and death, but oneself remains youthful forever. He and Uncle Zhao depended on each other for life, but they bumped into the First Emperor's Luan Jia on the streets of Xianyang and risked their lives to save the dying Li Si. Since then, he has been involved in the torrent of history: Witness the iron blood of the Qin Dynasty sweeping Liuhe, witness the heroic spirit of the Han Dynasty; watch the red cliffs reflected in the war of the Three Kingdoms, and get drunk in the moonlight of the prosperous Tang Dynasty. He taught the prince, entered the central government, and fought against Japanese pirates and barbarians while wearing armor. Thousands of years are engraved in history books and in his ageless eyes. When his peers turned into withered bones, he was still walking in the world - is this bowl of elixir of life a gift, or the longest punishment?