So only about 30% of the debt is owed to foreigners.Some of these links are a little dated but in general the debt is owned by foreign nations (China and Japan typically the largest foreign holders), retirement funds (especially Social Security and government pensions), and the Federal Reserve is sitting on a good chucnk of it.
Here’s who owns a record $21.21 trillion of U.S. debt
who holds the us public debt
The Real Owner of the U.S. Debt Will Surprise You
Who Owns the National Debt? - zFacts
Who actually owns it is not especially relevant however because working people are the ones who are expected to pay - there is no one else who actually generates wealth - and their wages have been stagnating for quite some time.
The fact that retirement plans are such heavy holders of these "promises to pay" exposes the fact that a "debt jubilee" which has occasionally been seen in the past is probably not an option in the current situation.
In a traditional debt jubilee the wealthy got a "haircut" - usually to avoild further radicalization of the poor and shrinking middle class that threatened social stability. Today that "haircut" would effectively wipe out private and public retirement plans on which the poor and middle class are dependent.
I think that the question of who owns the debt is very relevant. If a large part of it was held by China, for example, then the whole economy could be in the thrall of the government of China.
What do you mean by "working people are the ones expected to pay"? Business leaders, who may well each have large personal surpluses and no debt, can, by their decisions, generate wealth. Certainly, rich people pay a lot of money in taxes.