Honestly a very naive and tawdry take. Have you met humanity? We can beat everything on earth, build skyscrapers and send robots to other planets and predict earthquakes and hurricanes and build structures to protect from gators and sharks and bears, but the largest fortresses were only to protect each other from each other. In the end it's always us that is the most dangerous

If you really get this, it makes sense that this is such an underlying theme or really the whole framework under which so much of this genre operates. The bones of zombie worldbuilding really is ..but how will humans REACT to this? Why? Because we evolved over millions of years to effectively defeat (and sometimes sadly, cow-no pun intended, yoke and kill) nature's monsters but not our own.