Earlier quoted context omitted.
There is at least one other way to look at it. These loans will primarily, if not exclusively, go to large financial institutions. Due to the wonders of fractional reserve lending, those institutions will get to loan out several multiples of the original $1.5T. Another way to look at it is that they've probably "printed" closer to $15T.
How does this work? Like any government can just print their way to prosperity? I mean you just magically put $15T into circulation? Won't this lead to inflation?
If you have ever taken a loan from a bank you are aware that you must prove to the bank that you are able to repay the sum. Based on the information they receive they will calculate the default risk and increase the interest rate accordingly.
Warning. Extremely simplified for ease of demonstration.
If you have a 50% default risk then someone else has to cover your missed payments. For every $10k you want to borrow the bank has to ask for another $10k in additional interest to cover the default risk. If your loan lasts 8 years that means $833 additional interest per year or around 8%.
Now, if you are a young poor person with a bad credit score then you might end up paying 5% on top of the actual interest rate. Negative interest: 5% - 0.1% = 4.9%. Positive interest: 5% + 1% = 6%. I'm glossing over compounding interest but the picture is clear. Negative interest rates are not going to meaningfully change the cost of borrowing money for the average person unless they get a mortgage that is backed by the value of the house. Meanwhile for rich people and companies who can get rates as low as 1% lowering the interest rate to -0.1% is almost like a cheat code. At those rates the money might as well be free.