slavery in ancient history fiction books

Alex is a young man who struggles to make a living in the world's biggest game (Ancient world). He works as a mercenary who does every job he can find. It's been five years since his suffering started. Ancient World creation was only possible by the World's greatest invention, "AI ZERO." Ancient World A vast planet Multiple times the size of Earth Ruled by Great empires, Big organizations, and hidden Shadowy associations. A Fantasy world filled with prehistoric animals that have gone extinct on Earth. The creatures humans have only heard of in fairy tales and old stories, Monsters beyond the imagination of humans, roam the vast lands of the "Ancient World." Everything was going well, but it all changed on that day. When the United States told the World "AI ZERO." and "Ancient World." technology was a gift from a very advanced intergalactic civilization. That has surpassed humanity in any way of life by an uncountable margin. Humanity entered a new era, and the Ancient World became humankind's most important part of life. Alex joined the game to make a living and support his family, but things didn't go as he had hoped. After suffering in the Ancient world, Alex returned five years back in time. Alex knows that the Ancient World is not just a VR game. Now with a new chance in life, Alex will get strong and reach the top while finding the truth about the Ancient World.