i wouldnt even try to explain it to a little kid as they usually dont understand what money is
This is a good point. Make sure they understand fiat money. I would teach basic savings account. How you can have an account and add or subtract money from it.
Then I would find some nice videos to back it up. Then go into digital money and try to show it in a very very basic way. Many parts of it for that age might be to big of concept.