Should I use Node or Node2D for a level manager as a scene?

this is a good take

If the LevelManager or it’s parents may move then Node2D, otherwise Node; you are correct this is a very minor difference though.

Jufofu (the game I’m currently working on) uses a simple Node for the main scene, because I don’t need to change its position.

Don’t stress too much about it, in case you need to change the node type to 2D then you can just right click on top of it and change it.