I fully appreciate your post. I, a third generation veteran, have experienced changed in perspective as I aged and matured. I tend to focus on U.S. participation (or lack of). Yes, context counts.
Our battle for independence from England was a decision yet fought on our soil and inevitable IMO. So the first war was good, according to Americans, by and large ...and bad to Brits, by and large. Same with the War of 1812.
The Civil War was very devastating for both the North and South ... yet both sides found a way to glorify it for various reasons.
The Indian campaigns facilitated expansion to the West but were horrific (and genocidal) ... but the U.S. wouldn't have become what it is without them.
The Spanish American War was an effort on the U.S.'s part to lay claim to the Western Hemisphere as its own (and, again, the U.S. wouldn't be the same, otherwise).
WWI was the U.S. picking sides in a European war that was the worst the world had seen (until a few years later with WWII) but the entry of the U.S. finally cut it short.
WWII was a global conflict against fascism and we were attacked (I, personally, think that it might have been our one true just war).
Korea and Vietnam were proxy wars with communist China and the Soviet Union but they caused great death and destruction for the locals.
The Cold War was (is?) held our people and theirs as psychological hostages, fearing each other for or very lives.
The Middle East conflicts were rationalized actions of 'eliminating terrorism' (what a concept) by destroying places and people as an answer to a dozen Arabic extremists committing a terrible crime on our soil (but it also made a president or two seem more 'warrior like' and made stock holders richer - at a terrible cost to our soldiers, their families and the national treasury).
And so we're here ... on the brink with nobody really knowing what will come of it.
We've come a long way .... to nowhere.
When I was younger I actually bought what was taught out of public school history books, lock and barrel. Now, more detail came to light.