A sorta good way to explain the block chain in simple terms is to pose two scenarios. Scenario 1: I am over seas and need my (parent, freind, spouse) to send me 2k, they agree and let their bank know, to give me 2k. Now their bank contacts my bank and moves the funds and both banks make a note of it. Transaction complete.
Scenario 2: I am over seas and need my (parent, friend, spouse) to send me 2k, they agree and let our 5 friends know, each friend makes a note on a piece of paper(blockchain) and now we all have a record of it. So now if one or more of the records is damaged or lost or altered, we have more records to prove the transaction happened.
In scenario 1 the banks are the only ones with concrete evidence that the money was moved, if they lost or altered the evidence all that would be left was the word of the 2 parties involved.
This doesn't cover much but it at least gives a small real life example of one advantage of blockchain financing. You could expand on the story further and say your whole freind group or family keeps the records and after 10 transactions, they seal the paper away and agree to make no more changes to it. I also did not come up with this little story myself but read it elsewhere online and it was more eloquently written. Hope that helps someone.