Hot:

Martin Luther’s heretical bestseller
The 95 Theses

The Discovery of Coffee

Europe finally letting go of its colonies

The Invention of Fire

Socrates inventing his patented Socratic Seminars ™

The Scientific Revolution

Not:

King Tut’s early death (RIP KT 1324 B.C.)

“Sharing” used blankets in the New World

Invading Russia in the winter

Keeping the noble bloodline pure

Destruction of the Library of Alexandria

Rats with plague-infected fleas going on vacation in Europe