I think many in America may have a certain fondness for the British Royal Family, but since our founding involved throwing out the British monarchists, there has always been a strong anti-monarchist bent. Some may have loved the Queen from afar, but that's as far as it went.
Of course, many of the worst atrocities occurred before she became Queen, even before she was born. Britain had actually started to become more liberal, and most of Britain's colonies were granted independence. By that time, the U.S. had taken a more prominent and leading role in geopolitics, with the U.S. also favoring independence, as long as they could establish pro-Western and/or anti-communist governments. That would also appear to align with the interests of Britain, since US, British, and Western interests overall had become quite interconnected at that point.
I don't know how much the Queen knew or whether she had the power to make any difference in the course of world events. If she is to be judged according to the actions of her government during her reign, then one might still give mixed reviews. Americans might view it from an American point of view where Britain is considered our closest ally. Places where Britain occupied and committed atrocities may hold a different viewpoint, and that's fair. Americans also have a checkered past, much of it is indefensible.
