https://record.umich.edu/articles/lockdowns-saved-lives-but-...
So yeah, I do see your point in the lockdowns were probably unnecessary, but as others have mentioned, pandemics were new to the US at the time, and we didn't have the knowledge and procedures on how to best deal with it. Yeah, we did probably go overboard, but what happened is understandable given how deadly Covid was.
We know now that social distancing and masks (for those that are willing) would probably have been enough, as other countries used to pandemics already know, like South Korea.