China didn't invent money. The Mesopotamians did.

https://en.m.wikipedia.org/wiki/History_of_money

The establishment of the first cities in Mesopotamia (c. 3000 BCE) provided the infrastructure for the next simplest form of money of account – asset-backed credit or representative money. Farmers would deposit their grain in the temple which recorded the deposit on clay tablets and gave the farmer a receipt in the form of a clay token which they could then use to pay fees or other debts to the temple.[1] Since the bulk of the deposits in the temple were of the main staple, barley, a fixed quantity of barley came to be used as a unit of account.[45]

Trading with foreigners required a form of money which was not tied to the local temple or economy, money that carried its value with it. A third, proxy, commodity that would mediate exchanges which could not be settled with direct barter was the solution. Which commodity would be used was a matter of agreement between the two parties, but as trade links expanded and the number of parties involved increased the number of acceptable proxies would have decreased. Ultimately, one or two commodities were converged on in each trading zone, the most common being gold and silver.

In the introduction section of Handbook of the History of Money and Currency provides a glimpse into the relationship between grains and precious metals during this emergence of currency: "Grain was used as unit of account to calculate values, measure labor time and land yield, and as means of payment in agricultural and handicraft activities. Silver was used as means of payments for taxes and fees and for long-distance trade."[47] Stability of this type of currency was enforced by the ruler and backed by temples at that time. In essence, to reduce complications and nuisance of trading and bartering, grain and silver were utilized by early civilizations because they were portable, had use, and were divisible.

This process was independent of the local monetary system so in some cases societies may have used money of exchange before developing a local money of account. In societies where foreign trade was rare money of exchange may have appeared much later than money of account.

In early Mesopotamia copper was used in trade for a while but was soon superseded by silver. The temple (which financed and controlled most foreign trade) fixed exchange rates between barley and silver, and other important commodities, which enabled payment using any of them. It also enabled the extensive use of accounting in managing the whole economy, which led to the development of writing and thus the beginning of recorded history.[48]

Also

https://worldhistoryedu.com/the-history-of-money-when-were-coins-first-used-and-by-whom/

Egypt, Ur etc...

You could just re-melt the sprue and use it to make the next batch, right?

What puzzles me is the lack of vent holes to allow displaced air out of the mold once it's assembled. (Unless they're on the other half, the one that's not pictured here. That seems doubtful.) So whatever this was meant to cast must have been a very runny metal with a low melting point, probably with the mold itself being piping hot as part of the process as well. Probably not much of an alloy, and probably very easy to melt again.

The inscriptions on these appear to be awfully similar to some of those listed here:

https://en.wikipedia.org/wiki/Xin_dynasty_coinage

Wikipedia mentions these specifically as being cast, and in big batches with multiple molds filled in one operation. In light of that I'm surprised that the mold is so small. Check out this sumbitch, for instance, which makes 42 coins in one go. That seems a little more like it, if you're going to go through all that effort.

I'm reading that apparently what with one thing and another, the Chinese were still producing cast rather than struck coinage all the way up to the very early 1900s. Their currencies changed a lot throughout their long and never-ending parade of civil wars, overthrows, usurpations, fractures, and reunifications, and it seemed every time their leadership changed it came along with a reinvention of all the coinage as well.

What are you talking about? Just do a search for chinese coin and this are the perfect mold for them.

It will make coins.

https://en.m.wikipedia.org/wiki/Xin_dynasty_coinage

The image isn't this exact one, but you can see the mold must work on the same way. With a thick rim and slightly raised symbols on the inside.

Sorry, so your issue here is that the specific piece alone doesn't make coins?