I believe the statistic referenced in this headline is roughly total sum of debt in the world (184 trillion) / earth population (7.6 billion) is the total number of debt per person. I think what you are driving at is exactly why this article is misleading.
edit:
I don't think debt is exactly zero sum. When a loan is made, the person who took the load has a debt of the present value of future loan payments(ie with interest accrued and adjusted for inflation). The lender has an asset that is the present value of the loan payments times the probability the loan will be payed off. I might be missing something here though.
Right, if you have US government bonds (or a bond fund) in your 401k, that's included in the total. Your savings is also loaned out to others, and counts toward this number.
edit: I don't think debt is exactly zero sum. When a loan is made, the person who took the load has a debt of the present value of future loan payments(ie with interest accrued and adjusted for inflation). The lender has an asset that is the present value of the loan payments times the probability the loan will be payed off. I might be missing something here though.