Forced Apprenticeship System

What exactly is history? If history cannot be changed, why does time travel exist? If history can be changed, then why do all your efforts end up in vain? How did Zhang Jiao die, why did Guo Jia die so young, why did Sun Ce's temperament change so much, and was Sun Quan's rise to power really the result of God's will? Why did Guan Yu's head come back to life? Is Cao Cao's head wind disease really an incurable disease or is it just a cover-up for Cao Cao's death? Zhuge Liang's fire from the Southern Barbarians greatly damaged his moral character, and his five feet were inlaid with stars. Is Zhuge Liang doing it for himself, or is he desperately trying to protect Wei Yan, whom he accuses of being rebellious? In the Three Kingdoms before the Five Husties disrupted China, was it a choice of history, or was there an invisible black hand quietly manipulating everything? It's possible that the history in your eyes is just a picture in someone else's hand, put in your pocket, and changes its trajectory according to your mood...