Hi there
What's the most simple way to describe what bitcoin is for people?
Will be cool to read in the comments some new creative ways to do that!

It is hard to explain to a 7 year old kid what is bitcoin, and I think even if how simple you will say it to a kid they will never get interest with it. Imagine how hard to explain it to an adult and still they are not all interested with bitcoin. So, maybe it will still depend on a person how interest they are to bitcoin before they will understand bitcoin fully.
Well i'll describe it as something that they should be interested about when they grow older. Bitcoin is way beyond a 7yr old's capacity to digest and they should be focusing on playing and building a good foundation for eq.