1. Had the US not invaded Iraq, Saddam would probably have still been around. Which obviously means that ISIS would definitely be nowhere near Iraq.
It also would have meant having an evil, sadistic and power hungry dictator around who rules with an iron fist and a reign of terror on anyone who opposes him in Iraq, which is an extremely terrible option to have to choose, however unfortunately time has shown us that it probably was the least terrible option to have by some margin. Same applies to Arab spring countries, especially Libya and Syria IMO.
2. I think the US should not have been in Iraq at all in the first place, because that is what caused the vacuum of power that ISIS has taken advantage of. I think the insurgency in Syria like the one in Libya while most (ordinary) people who were for it(myself included btw) had different hopes in mind, unfortunately countries like those(and Iraq) who do not have any legitimate institutions in place and were completely dependent on previous dictators and their small tightly knit circle of influence, inevitably face absolute chaos when those dictators regimes are taken down, and no group in this region are as organized and as prepared to be able to take advantage of such chaos as radical groups are. So what inevitably happens is those radical groups create strongholds in such countries, and when they have such strongholds they then have access to resources that allows them to spread their terror all around the world. The countries they occupy are much worse off of course. Iraq, Syria and Libya are absolutely devastated by ISIS and their ilk. Yet people like you want us to apologize for the very people who have caused us more misery than they've caused you.