Delete all nodes we used for testing
How does Main know which level to load?
To keep track of data that needs to move between scenes use an Autoload Global Singleton
This is a script or scene which the Godot Engine will automatically load at all times.
Even if you change scenes, the autoload will remain and is globally present and available.
Right-click in the FileSystem and select
Create New => Script
Save the script as game_state.gd