I Guard The Book That Slays Gods - Chapter 45: Message to the Kingdom 2

“In order to survive the future great war, we must take drastic measures. We need to summon warriors and train them before time runs out.”Thus, millions of earthlings were reincarnated in an alien, medieval world governed by swords and magic to save its prophesied doom.Among those individuals, one's situation inexplicably deviated from the others.Thrust into a rotting house in a ghostly body, Adam found himself bound to a wailing baby. With a heavily damaged soul and the snarky remarks of a system, he began his years-long quest to recover his body.Armed with his mind, he'll educate the baby and slowly watch him turn into a good youth. However, he would have to make a choice: suffer as a ghost until he finds an alternative that might not exist, or possess his body and reincarnate.He was far from imagining how dangerous this world full of possibilities could be, prompting him to question everything he knew... Including himself and this world's intentionally blurred history.

He lived from BC to the Middle Ages, from the Renaissance to the Industrial Revolution, and from Cyberpunk to the Interstellar Age. He has been a king and a prophet, a knight and a nobleman, a versatile artist, a genius inventor…
This is a four-thousand-year human epic——
“To us four thousand years from now:
“Is the world at peace? Is famine extinct? Can people touch the stars? How long is the human lifespan? How far is the boundary of the earth? Human…do you remember us?”
——Excavated from Earth Age Tenth Century BC, Solomon Prayer Book.

- Description from novelbuddy