A "blockchain" is a decentralized way to store data. Basically, all participants keep a copy or, at least, a hashsum of the "database" on their computers. Every time a new dataset ("transaction") is added, it will be based on each previous transaction. (This is why Bitcoin transactions are taking so long to complete.) If any inconsistency is detected between the various participants (usually, many of them will have to "confirm" a transaction before it is considered valid), it will be dropped. (This is the ELI5 explanation. Technically, more things happen.)
Cryptocurrencies are Ponzi schemes, using blockchains to achieve their "goals".
Those are different things.
So we can create as many Bitcoins as we want?
Yes, you can. If you have enough computing power, that is.
Thank You for Explanation! 😁
The total amount of bitcoins that can ever exist is 21 million, Of which ~18M is mined.