But not every beneficial outcome implies a voluntary choice.
So by your own definition of economy even a lot of human interactions turn out to be non-economic.
By defining humanity in your way you just limit yourself to that part of a human being that is of interest to you or the rest of the economy.
It fails to cover all of human interactions and it fails to cover most of the rest of the universe unless you want to confuse it with energy and information flow.
But then you have to let go of the 'voluntary' part.
The thing is, a lot of the properties that you consider economical are in fact based on general non-voluntary interactions and have nothing to do with economics unless a human takes interest.