RE: BLOCKCHAIN FOR DUMMIES - what would be your explanation? [question from my recent interview]

My instant and impromptu answer....
I would start by saying "Do you you you can use the computer to record and store information?"
Think of a blockchain as a large number of computers running the same software.
This software enables the computer to talk to each other and create a log very much like a physical world note book.
This network keeps a record of what is happening in the network or blockchain.
The idea of having a blockchain is to log information such as transactions between two people.
Since it is not one computer instead a lot of computers running the software we also refer to these computers as nodes.
Together they act as a peer to peer network where each node contributes in sustaining what is known as a decentralized ledger or log of transactions.
Well this was the idea behind Bitcoin.
I feel this should be enough to explain the idea of a blockchain. If you want to go deeper one can elaborate about the rewards of running a node . How it provides stability and how rewards for validating transactions are distributed.
A little insight into how I arrived at this way of answering
I did a mental map where bockchain==> Bitcoin
How was the bitcoin blockchain and I put together my thoughts..Dear @crypto.piotr

I think the next time you face such a question think of bitcoin and explain how the bitcoin blockchain works.
Since your information and level of understanding is much advanced you may find too many ideas and complex solutions popping up in the head all at the same time.
So to keep it simple and noob friendly one could answer w.r.t bitcoin and its blockchain.