For the chuckle

... aliens

How so?

I mean- it's arguable. But in general the "richest" person in a room is the one who owes the most money. But the underlying sentiment of not having money without debt is that most currency is a promissory note. A $10 bill is literally a $10 debt in your pocket. That government has promised to honor that debt. The money itself is worth only as much as any piece of paper. All that gives it worth is that a government has said they'll cover the tab for X amount on the bill. Same with credit or gift cards- they're worthless except a company has agreed to pay the debt of the card to a limit. When money represented gold in a treasury bills were just notes of gold debt. Once they stopped that they became imaginary debt. In societies using precious metals like gold for money- unless the actual gold value of the coin equals its face value there is debt at play. In general money is a placeholder for debt, just a paperwork system to keep track of who owes who what.

Correct, money is an indicator of how much debt is owed to the “owner” of the money. All other methods of payment such as gold or gems are simply part of a barter system.