if humans invented the "economy...."?

The study of economics is considered a science. It attempts to explain how and why economies work, not invent them. It is more a less a study of human nature. In fact, economies existed before people had ever defined what an economy was.

As per your example, there are such economies that don't have money. It is called a barter system, and it really doesn't work very well on a large scale. I suppose you could also eliminate all money from a communistic system and simply ration goods to people as payment for labor. It hasn't been done that way, but it would most likely fail as all large communist economies have.

They way the economy works is due to human nature, not a rational design. Changing it is analogous to everyone making a resolution that they will be understanding and nice to other people, but most of us can't even get through a day without getting irritated at another driver or yelling at our children. Considering what we use to do, our current economy is not that bad, at least we no longer make slaves of people on a large scale to do the work, and most of us do not depend on pillaging and plundering to get what we want.

Because rich people are still in charge of the world. No matter what solutions any of them come up with their main goal is to keep the rich people happy.

because we don't currently have a time machine that works.

you can't just erase the workings of modern day economics and government.