I don't think Covid-19 has shown that. A lot of world leaders maybe took a bit longer to react than they should have, but once it was clear that the virus was spreading they acted sensibly to prevent widespread contagion and those countries now have rather low infection rates.
Some other leaders (i.e. Bolansaro, Modi, Putin, Trump, and probably some other leaders of countries where we don't even know how bad the situation is) have reacted poorly, leading to less good results.
Even in places like the United States which has been doing a terrible job, I am amazed at the scope of sacrifice that has been made to prevent the potential of millions of deaths, and by the generally high level of compliance with social distancing. It's not good enough, mind you, and those sacrifices will be for naught if we don't eventually get things under control, but having 90% of people in stores wearing masks is a lot higher than just about anyone would have guessed if one were to suggest this scenario as a hypothetical a year ago. I think most health experts expected about 50%.
Really, the whole world has been quite united I think on average despite poor leadership when you look at the actions of individual people. On the other hand, as pandemic fatigue sets in that early solidarity seems to be getting weaker.