1. Our economy is built on slave labour. That's how Europe became prosperous and expanded out into its colonies. The world order was established at that point and prevails.
2. All parts of our welfare system use the Victorian notion of deserving and undeserving poor apart from healthcare which is still, as near as dammit, undiscriminating and truly universal.
3. The longer lived we become the more risk averse we become.
4. The size of the global economy is meaningless as money has no intrinsic value. We only trade with ourselves therefore it's a closed system which you could call 1. If you quantitively eased the global economy by adding $100 or $1000000 for every $1 you could still call it 1.
5. Given the above, national debts have meaning only relative to each other. Again you could multiply them all by a factor and still be in the same position. As there is no 'cash-in' day there is no limit to how much debt can continue to be rolled forward by a nation.
A person on the other hand has a lifetime - so there is a built in cash-in day. In prosperous countries roughly half of that lifetime is spent as a planned cost to society (20 years childhood and 20 to 30 years retirement) while the remaining half is supposed to pay for all that as well as the costs of living during that period and the other running costs of society. Oh, and you also have to pay for the last bit of education.