Comment by arter45

If we're talking about big science&technology categories, I'd say:

Controlled fire (if you can consider it a "man-made creation") -> essential for food and a lot of manufacturing

Wheel -> essential for transportation, but also to make flour (millstones), and a lot of other stuff (e.g. turbines are, basically, specialized wheels)

Controlled electricity and electromagnetism -> artificial light, modern communications, not to mention medical advancements like X-rays

Insulin and pecillin -> millions of lives saved

the printing press -> knowledge becomes easier to spread

If we extend this to all kinds of human "inventions", including law, philosophy, religion, and so on, the list is even longer.