How to make Multi-character system

I am looking for help making a system of many characters as found in games such as:

  • Overwatch
  • Team Fortress 2
  • Paladins
  • Leaguage of legends
    but I don’t know how to do it. I thought each character would have their ID to which the game would refer by changing skills and life points, appearance etc.
    but for some reason it doesn’t work.
    That is why I am asking for help how to make a system that will work.