I am not sure how many of you have ever played the "Civilization" game series, but I find it interesting the order of scientific discovery:

Alphabet
Writing
Horsemanship
Religion
Chariots

and so on.

I would also add to my earlier post, the second most important human invention: Mathematics, which forms the basis of all our hard sciences.

a few more

Simple machines, like the Lever, The Wheel and the Pulley, are the basis of our modern engineering

The solid state transistor and the Mircochip, which form the basis of our electronics and computing.