Should we gauge our actions and the actions of our leaders in the context of history? In the context of the times they were in?

Although I am a liberal, sometimes I fear that we are applying today's standards to yesterday's ethics and morals, which were admittedly flawed. I am not advocating that we forget and forgive the wrongs of the past - heck no! All I wonder is whether there is a better of way of teaching about our past than toppling statues and removing passages from our history. How about adding a conspicuous plaque that provides more information about a statue, a relic or an insignia?