Something wrong going on here with his webcam or whatever cam it is. Does this webcam/cam even work outside of OBS Studio? Make 100% sure it does. If it doesn't, detach it from the computer and any sources associated with it. Go get a new Logitech C922 instead.
21:28:57.453: Cam: data.GetDevice failed
21:28:57.453: Cam: Video configuration failed
21:28:57.803: Switched to scene 'Gaming - No Cam'
This game capture source looks fishy also. This is a warning, and then continues processing.
21:28:57.449: [game-capture: 'terra'] error acquiring, scale is bad
Why do you have multiple game capture setup as sources? Use only one source game capture and adjust the Window title whenever you change games/applications. Treat the Game Capture just like you would treat a physical display capture monitor. Only one is needed.
21:28:57.898: [game-capture: 'fort'] attempting to hook process: FortniteClient-Win64-Shipping.exe