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.

Most important, because that's how most people start and grow their business, they don't have multimillion inheritance.

Also buying house.

You (and the other guy that replied) are indeed thinking of usury (which is a very evil thing, even frowned upon by most religions), which is the situation of lending assets to for the sake of profit

Debt on the other hand is a more general concept, did you ever borrow a pen from another person? While you were writing you were in debt for that pen (but this is a silly example that can be disregarded)

Did your parents take care of you as a child? In most cultures, thar means you're in debt and owe them care when they get old (though I understand that this varies from culture to culture, but the idea is there anyway) If you are friendly to your neighbors and they invite you home to dinner several times, you are also expected to pay back the favor sometime down the road, this is another form of debt

To sum it up, debt is much more intrinsic to our behavior as humans than we usually think, even though "formal debt" might not be

Even if you're able to make that work on an individual level (never buy a home, don't get higher education, make sure you don't need a car), you can't make it work on a societal level.

If you want to contribute to supplying houses to people, you need to build the houses before you can sell/rent them (mostly). That means you need to take up a loan to pay for everything involved in building houses. Then you can sell/rent the houses to individuals that don't want to take up loans. Regardless of whether you personally ever take up a loan, you likely wouldn't have housing without someone doing it (unless you live on a family farm from waaay back), because the people that built it needed a loan to do so.

Well, it solves the problem of "I'm 25 years old with a decent paying job but no saved up capital, and need to buy <house/car/etc.>". Without taking on debt, I would need to save up for years to buy this stuff, but by taking on debt I can buy it now and "save up" (i.e. pay back) over the next years.

By all means, loans should be regulated in order to prevent people from taking on debt they can't afford, and to prevent/punish predatory practices. Debt in and of itself however can be a very good thing.

I have an apartment and a car now, with down-payments that I can afford without huge problems. Without taking a loan it probably would have taken me 25 years to be able to afford this. Except I wouldn't have, because the money I'm now using for down-payments would instead have gone to paying rent.