Asklemmy

The Tamagotchi - for obvious reasons.

Fire. The rest followed.

Written language. It lets us speak to people across time.

I don't know if this counts, but I'd say the Enlightenment. It was a discovery in that we discovered a new way to interpret the world.

I think there is kind of a glass ceiling when you talk about fire, plumbing, electricity and so on. Each one was a necessary stepping stone to get us where we are, but without any one of them, we wouldn't be here.

The Enlightenment gave us a brand new sense of autonomy as a species, which in turn has given us a greater amount of control over "Destiny."

I'm not sure about the greatest invention but the second greatest is sliced bread!

Sliced bread. Before sandwiches what was the point?

Screw the running water and antibiotics. I don't need no machinery or amenities, give me cheese!

Computers are cool though

Electricity

Literature, Writing, Written Word. If we couldn't document and share ideas, we'd be nowhere.

Language without it we wouldn't be able to work together. Therefore inventing things would be almost impossible without it. Science and technology require corporation which requires language.

Microwave. Being able to heat up a hot pocket in just minutes is legendary.

The printing press. It allowed us for the first time to share knowledge at a scale we only dreamed of.

The ability to shape steel. Sounds basic but blacksmiths make the tools for everything else.

The wheel and the derivatives of the circular shape in general; they powered all human innovations from abstract mathematics to real life applications and everything in between.

Copper. Because without copper, most of the named things wouldn't be possible to create!

The microwave.

Can you imagine having to cook every night?

Central air

Spray cheese

Irrigation. But Iron Working and Celestial Navigation are good shouts too.