Do you own a home? Do you think that's a worthwhile thing to do? Without debt, home ownership is basically completely out of reach for most people despite the fact that many people will earn enough money to buy a house in their lifetime. It allows you to pay for money now with money later. Debt is legitimately an extremely important part of an economy- there's a reason it's been invented by pretty much every agricultural society in history. As with most financial instruments, it started with farmers - it costs money to plant and grow a crop of grain, but that crop doesn't produce money until you sell it at harvest time so you have an issue where if last year's crop didn't go so well due to weather and you are low on cash in the spring, you can't afford to plant next year's crop and get out of the hole. So borrowing money is the easiest way.

This also works with businesses and governments. Say you want to buy a machine that prints designs on T shirts because you want to sell T shirts. You can't afford the machine now, but you believe that you'd be able to with the money you could make from your T shirt business, so you go to the bank and convince them of the plan, and they give you money up front. Without debt, that T shirt business couldn't happen unless you got a bunch of investors to help you out.