Checks are of course a product of banks, but I fail to see how that should have brought significant change (rather than a bit of convenience). They were certainly never more trustworthy than cash, and they are themselves not more than simply a form of currency. Things like credit agreements are a separate product.
>I fail to see how that should have brought significant change (rather than a bit of convenience).
A bit of convenience can create massive change. What's the difference from online banking compared to buying at a store other than a bit of convenience? You can do all the same things in person, yet we've seen massive changes in logistics and ourchasing habits because of it. Checks that people _trusted_ were massive. You could write someone a document that let them go to somewhere nearby to get gold, rather than carrying it on the roads. This was the modern era where you can travel most European or american roads safely. The world wasn't lawless but the law didn't extend much farther out than the local rulers could patrol. There was always the risk of bandits taking your shipments on land or pirates on the sea. By having a banking system the risk of transferring currency dropped massively and that would lead people to engaging in enterprises that were too risky previously
Also if hard work led to you having wealth then their wouldn't have been peasants, and even children could buy their own homes after a long day in the fields or mines.
I am an avid critic of the financial industry, but the whole idea of lending money and having a store of it that was trusted enough to accept checks from altered all of society. Prior to that you could only purchase as much material as you had money on hand to buy, or something else to trade. There was no way to borrow 100 dollars to buy materials that you converted into 130 dollars of value without already having 100 dollars