As a finance guy I don't see a lot of core innovation. Somehow I've been able to understand pretty much every financial instrument I've come across using a few basics that you learn immediately when you get into the business:

Time value of money, optionality, non-arbitrage.

There's a million ways to cook up a financial product from those and I'm not going to pretend I know them all, but it's like how a chef can look at a dish from another culture and still more or less describe what it is: sugar, fat, acidity, heat, etc.

When exciting things have happened in finance it's often been purely because the exciting thing became legal. Things like buybacks or the repeal of Glass-Steagal. The other thing that can happen is that some sales team finds a way to sell the thing that creates an ecosystem around it, like Credit Default Swaps. Rarely is it the financial contract itself that is so inventive as to create a market.