"and financial and economic losses in the other. The latter can certainly cause the loss of human life, but I haven't seen anything but hand-wavy attempts to quantify it."

There's a few reasons for that. One is that people are very reluctant to hear than there is a finite limit to the amount of money that other people should spend to save their lives. Another is that it is highly situation-dependent, so there really isn't one solid number.

Nevertheless, yes, at scale your mental conception of "economic damage" is probably incorrect. You are probably, if you mentally examine your conceptions, basically taking all the economic damage as coming out of "discretionary income"; who cares if we all lock ourselves up for a while and as a result, people can't buy the 65" new flatscreen TV they wanted and have to stick with what they have? Were that the truth, yes, economic damage would be something we could basically wave away.

It is not the truth. The economic impact does not entirely come out of discretionary income. Connect some other pieces in, such as the HN favorite "Most households can't handle an unexpected expense of a $1000." Connect in the fact that poverty isn't just not buying flatscreens, but food insecurity, childhood stress that we've had links to studies showing the long-term negative impact of, and the general badness of poverty. Economic damage is true damage, and will in the long term kill people. Moreover, we are choosing economic damage now that will persist for months or years, still hurting people, after the coronavirus would have been gone. It also hurts the poor more than the rich; frankly the coronavirus up to this point has hardly affected me personally at all, but that doesn't mean I should underestimate how it is affecting others. At the moment I can't name anyone who has been totally, utterly "fired" to the point that they are guaranteed they have no job to come back to, I can name many names of people currently not being paid, who may or may not all be made up by government checks.

Also note I'm not making a new argument, I'm still just defending my original claim that the range of possible outcomes is so wide that there are non-trivial options where coronavirus would have hurt less than a full lockdown. (Especially if you include other options, like, "tell everyone to wear masks, even impromptu ones made of T-Shirts over your face, wash your hands, limit social gatherings and cut schools (huge germ transmitters), but otherwise let the economy go. There's a lot of reason to believe that would have worked fairly well, beyond the scope I can go into right now.) But economic damage really will hurt people.

(On the other, other hand, it has been observed that the total death rate in the US is down right now, which also factors in somehow.)

Basically, I'm saying there's plenty of other contexts where we have no problem saying that economic hardship is really, really bad. It should be the same in this context, too. Otherwise, the next time someone is talking about how bad poverty is for someone, intellectual honesty would compel you to dismiss that argument the same way you are dismissing the idea right now that economy hardship is bad. If you are unwilling to agree with the proposition that "economic hardship isn't really a big deal in the long run" in that context, you shouldn't be agreeing with it in this one either.