How did you get the Not Human bool that’s causing an error in your game mode? It’s not a variable that’s present in your game mode, so it’s normal that you are getting an error.
Did you drag and drop it from your menu BP into your game mode BP? You can’t do that, and the result is that it’s trying to find the variable but it can’t because it defaults to “self” (the game mode BP) as the target.
When you use Open Level, all blueprints (except Game Instance) and actors are destroyed and then re-created once the level finishes loading, but none of the values carry over. The only way to carry over data from a previous level is to store it in the game instance (or a save file but that is more complex), which I see you’re already doing for something else.
You should have the “Not Human” variable in your game instance instead of your menu, and change it in the game instance from your menu, then fetch it from the game instance in your game mode.