You're not Winger, Sealy! When you work for Government it's all about seniority. If you've spent a decade and a half working in a department and you've only become a "low level supervisor" then it's pretty obvious that you're either a world class idiot or you show up and just go through the motions because you know it's almost impossible to bet fired from a Public Sector job!
As for why they made that other guy your boss? Isn't it obvious? He's probably BEEN showing up early and staying late! When you do that in the Private Sector you tend to get promoted.