Hey! There is a ton to learn here. I found this video below did a really good job explaining the fundamentals of what a blockchain is. At the most fundamental level, a blockchain is a shared ledger. With some cryptography, networking, and some game theory we can create a system that allows anonymous folks sharing the ledger to agree on the state of the said ledger. Pretty amazing stuff!
Check this video out, I think it will help clarify some of the basics: