What are the biggest mistakes in human history that shaped the course of history in your opinion?

What's wrong with Croms

The mutation of Indo Europeans that lead to white people.

this could be a fun thread
norman conquest of anglo-saxon england
alexander dying because lol sick
atilla dying because lol sick

Unironically this.

Ogedei Khan dying at an inconvenient time
The Mongol army was halfway into its invasion of Europe, but the death of a Khan means the royals of every tribe must return to the capital in order to witness the coronation of the new Khan.
Ogedei had given the army license to push through all the way to the Atlantic, and it's fairly likely they would've done so, given the outcomes of their previous encounters with European armies.

Meme. Xerxes would've inevitably overturned that position regardless
Salamis, Platea and Marathon were all more critical

The barbarian invasions

rip

Democracy.

Christianity

Julian forgetting his fucking armor.

He's referencing Constantinople ya dinguses, not Thermopylae.

Cromwell and the death of the true god emperor

Gavrilo Princip

The fuck is that portrait I have never seen it before even after studying the Stuart's for years
But yeah biggest mistake was Alexander's father not having more children
Also letting Napoleon unite the north Germans