Money or types of currency have been used since 700 BC. Since then it has been a way for people to fall into a certain social class and also so that everyone would not own a $500,000 house.
That is not correct.
Read Nick Szabo's groundbreaking paper about the origin of money (it is not that long, and it is a fascinating reading really!)
http://szabo.best.vwh.net/shell.html.
In this anthropologists, archeologists, evolutionary psychologist presents the facts that money, or money like instruments - they call them collectibles - were used no less than 70.000 BC AT LEAST, waaay before bartering or trading itself emerged from exactly the new possibilities money enabled. Without money (collectibles, - the ability to hoard and communicate wealth and "favors" among humans, THROUGH SPACE and TIME with moderate or no TRUST), so without money abstract there would be no civilization !!!!
Homo sapiens sapiens is the only species on Earth capable of wealth transfer between descendans and ancients through using money/collectibles/titles/deeds to pass on to their children.
Also, there are no "classes". Having 100$ per year as an income or 10000000$ is not a qualitative difference, it is a quantitative one, in principle they still have the same societal boundaries (right to own property given they trade it/laws to be obeyed by everyone), just less or more wealth doesn't create classes (you could not separate them anyway, a poor lower class citizen in the U.S. is probably still in the top richest 3% of the Earth's population. Good luck with classification and marxism
Slavery was the last "class society", where we had "zero income, no right to property (as the ground zero property right is to own one's own body!) at all" class (slaves) and "non-zero income with the right to have property" class (everyone else). That one is a qualitative difference!
About the 0.5M$ house: there are cheap and expensive houses because of scarcity of supply against huge demand, or vice versa.. Example. There is a fixed amount of housing that can be built looking at Central Park/Eiffel Tower. So those going to be more expensive ones because they can only facilitate a fixed amount of tenants which is a smaller number than how many would like to live there, price goes up etc etc. Supply/Demand.
In this example it shows perfectly why you CAN NOT eradicate money. Why? Because without it -aka it is free, how o you decide which 500 of those 62670 people who want to move in next to Eiffel tower actually does? Lottery? Violence? Would pure luck or strongest surviving ethically superior to voluntary exchange of marginal utilities?
No answer i guess, because money is just a conflict avoiding solution to a a physical fact that: time,space, and resources ARE scarce, and if demand>supply, somehow humans need to solve this equation (preferably non violent).