What it the worst war in human history?

WW2 was the worst war in human history because it had 40,000,000–85,000,000 deaths, and it lasted from 1939–1945.

I believe it is the World War II.
because,
1. It generated 50 - 80 MILLION Casualties worldwide
2. Created two conflicting superpowers the United States of America and the Soviet Union.
3. Became the roots for the Cold War
4. Destroyed historical and prosperous cities (example, Manila, Dresden, Cologne, London)

but it also fostered good benefits
1. Innovation in aeronautics recovered in Germany (The Vergeltungswaffe 2 rocket [Basis of the Apollo Rockets] and the H0RTEN H0 229 [Basis of Stealth Technology])
2. Gave independence to Colonies
3. Led to Nuclear Development
4. Led to the Space Race (Part of the Cold War [Led to placing humans in the moon and satellites above the earth])

that's all I know, have a good day :)