The problems in Syria are ancient, going back to at least Byzantium. But the modern problems are the results of European imperialism. Actually, Woodrow Wilson tried to make some sense out of the post-Ottoman Empire middle east by proposing, and then actually doing some research among the people of the region themselvesto come up with some kind of self-determination plan that might have a chance at working. But the British and the French had already secretly made a plan for the sole purpose of benefitting their own imperialist interests, and thus, we have the middle east as it is today.
https://www.theatlantic.com/international/archive/2015/02/the-middle-east-that-might-have-been/385410/
Maybe our response should have been to let them take care of the mess they made, but neither of them was either militarily capable, or politically competent to do so. We would have been more involved then, perhaps less so now because the political situation we currently have would never have developed. It's hard to say what would have come out of Wilson's proposal, but the US would have eventually let the mandates go and backed out.
I've run into many Syrian refugees here. One of the biggest tragedies is that the remnants of the Antiochian Orthodox Church, one of the oldest partriarchal churches of Eastern Orthodox Christianity, devastated during the ISIS occupation, is now being decimated. The Kurds tolerated and protected the presence of the Orthodox, but ISIS didn't. They had some hope when the Kurds succeeded in driving out ISIS but that was dashed when Trump turned his back on the Kurds and opened the door to Turkey and to anarchy. The last few congregations left are either fleeing for their lives or being murdered.