Return to the fundamentals that made this country great to start with.
Slavery and stealing the native people's land?
If you MUST focus on the 'negatives' of the founding of the USA, please refrain from asserting such as 'founding doctrines' as neither of those you state are factual or accurate as you imply. If one cares to do some research, they will find that most of the US physical land was 'owned by no one! Native tribes constantly warred over territorial dominion but never claimed 'ownership', only rights to exploit whatever resources that were there. Those few areas that were claimed to be 'owned' were paid for in almost all circumstances in one form or another. Face the facts, native Americans were truly stone age civilizations in the trues sense of the term. That being a fact, what or how else would you have dealt with them? Sheer armed conquest and genocide was readily possible and probably considered. (In later days in the west it was covertly exercised to some degree) So I suggest that your first point is little more than a 'straw dog' postulate.
As to slavery, it was certainly in no way a 'founding doctrine' of the nation. Study your history and you will find that at the earliest points plans were put in place to deal the elimination of this practice, only later to be ignored. Much of true history of the slavery issue has been intentionally forgotten, I can only speculate why but with intentional research you can still find the truth of the matter. I am not defending slavery or making excuses for its being part of the history of the US, but please don't claim that is one of the founding doctrines of this country, at best you could state that slavery was an existing issue for which accommodations had to be made.