My where do i start?

Language - to allow homo sapiens cooperate and coordinate beyond the limits of grunts and hand signals.

Culture - to allow homo sapiens to exceed the limits of the Dunbarr number (https://en.wikipedia.org/wiki/Dunbar%27s_number) and coexist peacefully with each other beyond their immediate family members.

Religion - to allow homo sapiens (now Humans) to coorperate and coexist with each other over different cultures. Humans managed to band together by the hundreds of thousands and perform feats never seen in the natural realm. Religion also enabled the worst evils of mankind. impressive in nature too despite what we humans feel about it.

Money and trade - to allow humans of different religion to coexist and trade value, and create economies

Agriculture livestock - When one species controls it's source of food, what is impossible for them?

writing system - by recording things on physical objects and later readily retrieve and interpret them, we've literally outsourced memory away from our brains.

Humans' greatest achievements are often the most overlooked and least talked about. These things look rudimentary to us now, but these are the very inventions that separated us from animals.