I don't think you need to explain cryptocurrency from the technical point of view. Just like we explain the internet: it is an information protocol. We did not explain about TCP/IP and IP v4 stuff. Just mention that it is a digital currency where money can be transferred quickly with a reasonable fee. And then show the wallet, how to transfer, and stuff...
But that does not explain it...if you just say it's digital money. What is digital money? Who created it, how can it be worth something. I think your explanation is simple but yet too simple to be real explanation.