The first cryptocurrency was Bitcoin created by Satoshi Nakamoto "Unknown programmer"

According to the Bitcoin white paper the main purpose of Bitcoin was to enable peer-to-peer trade using electronic cash. At the time there was no such a definition like cryptocurrency.

The big question which should be answered is what was the problem of existing electronic cash at the time. Before Bitcoin people could not buy and sell things without middle man. It is very easy to overlook that every bargain need someone to guarantee the contract. For instance when people use credit card there always need to be credit card company to assure the transaction between two people, and the company's role gets more important to make sure there is no deceiving among traders. Also, when people use smartphone banking it seems like the money transfer by itself without any help, however the bank have to look after the money to make sure sender and receiver gets the right information.

After knowing the existence of middleman like bank and credit card company, next question is why they are essential. Usually digital data is easily reproducible it can be copied without any difficulty. Therefore, if bank doesn't build up their own security system anyone can be billionaire simply by changing the number.

Blockchain technology enabled peer-to-peer exchange by the distributed ledger. Distributed ledger prevents copy and editing because every people share ledger which all the transaction is written on. This is the major difference between cryptocurrency and other digital currency.