Other things that are surprisingly less than 100 years old include electronic music, Germany, Croatia, capitalism, the end of slavery, worker's rights, fiat currency, central banks, stock markets as more than a niche thing, and so on.

What year do you think it is

While there was legal slavery in some countries well into the second half of the 20th century, capitalism and workers' rights movements are definitely older than 100 years.

Didn't the Dutch East India Company go public in 1602?

Also, in ancient Rome, coinage with Caesar's face on it was traded above its bullion value. They'd kill 1/10th of your population repeatedly until you agreed to this (such was the origins of the word "decimation"), and then they'd buy their dinner from you with caesar-face coin and move on to the next village tomorrow. Now that you have some caesar-face coin, you have some incentive to continue upholding its inflated value, and the tax collectors will show up later and re-apply threats of violence to ensure that you continue to do so. That sounds like fiat currency to me.

Also, the federal reserve was established in 1913.

Dude, I'm all for framing the status quo as mutable, but maybe do a bit of research.