Where to learn about Financial instruments and then DeFi?

Does anyone have any recommendation for resources on where to learn about financial instruments?

I have a feeling I struggle to appreciate the world of DeFi, as I do not fully comprehend what is possible in the world of finance, that is then being decentralized with DeFi.

Right now it seems yield farming and borrowing is what people mean when they say DeFi but I have a feeling it is more fundamental than this.

Anyone have suggestion of stuff to read in other to appreciate both financial instruments and how Blockchain is disrupting the space?