That is an immensely optimistic take on the situation
We don't even have the cost/benefit analysis finalised now, never mind at the time
It seemed to globally become a big Game Theory tournament.
You are right, there was no option for governments at the time - but this was politically, not practically. The calls for lockdown were loud and persistent from the press, I remember people pulling kids out of school the week before lockdown, voluntarily! As a politician, Game Theory kicked in, big time. There was "no loss" politically from doing the lockdown, which is exactly what Boris did, despite his instinct that it was a terrible idea. If he had done nothing - he would have been gone in a week or two, such would have been the push back (because of the fear mongering).
But that is not to say there was no other viable practical option - we could have negotiated our response based on health and economy rather than just health. As we are seeing now, you have to consider both of these things - you cannot just use one as the primary decision making criteria, because there will be push back on the other. The global cost of living crisis is partly down to the global response to the pandemic - lockdowns and destruction of the supply chains - and there is no doubt that is costing lives.
Sweden appeared to do this - evaluating both economy and health and thereby did not lockdown, they had restrictions but all schools remained open and businesses were not shut down. There were other options, we were just told there weren't.
Sweden did absolutely fine, and are definitely better off now.