You are missing the point. Forget all other spending. The revenue that comes in has to cover, and does indeed cover, the interest on the debt. The US Govt pays that bill first. It always has. Always will. It is like a family paying the mortgage first THEN the other bills.
But it would appear that — even using the gov’t own definition of “essential” — that it’s quite likely they were making those bills too (active military - yes, civilian military no, Social Security, Medicare; no one could retire during the furlough (although were retirees paid?), and I’m not sure what “income security” is.
Yes. Levin covered this recently.