School reopening timing varied all over the map, right? I don't think there was some specific date determined by "science" for any of that, everyone was seat of the pantsing. We also knew pretty early on that this largely hit elderly hard, not young folks, and not kids. The biggest mistake made in my mind was the notion that various steps would END the outbreak. Closing schools was intended to cut down on transmission, and that was never going to work very well. Maybe "we" didn't know it at the time, but I think "we" did know it by the end of 2020.
As for asserting this politician or that was critically damaging to the efforts, I disagree. The idea that just about anyone else as President would have done a LOT better is not something to which I subscribe. Nobody anywhere did a lot better except perhaps some island nations or nations that could be totally isolated because they are dictatorships.