Hey everyone!
I’m very new to Unity and game programming in general.
I have questions about these Unity pre-installed assets and packages:
What are they for?
Can I delete them?
If I can’t delete them, can I store them in a “Unity” folder without risk?
Where can I find documentation about them?
These questions seem probably stupid for you, but I need to understand my environment to stay organized.
You can safely delete most of them, but you’ll need to keep the Settings and InputSystem asset. You can move all of these into a subfolder if you prefer.
Deletable:
If you delete all Scenes, you will need to create your own scene. Otherwise Unity will always have an “Untitled” scene open and nag you about saving it, respectively if you have the scene open that you delete then saving the scene will recreate the scene asset.
The documentation for these is in the Readme. Just select it, this should show some text in the Inspector window.
Thank’s a lot for your answer CodeSmile !
But what about all of these packages ?
I also wanted to share this screenshot, but I can only share one per message.
I know I can delete them in the package manager, but are they necessary?
As a beginner, there‘s nothing you gain from removing any of these packages. You‘re better off just using Unity. 
Each package has a documentation link in Package Manager. You can check to see if you need it. If a package has the chain icon however the some other package depends on it and you can‘t remove it.
FWIW the two packages you can almost certainly remove are Visual Scripting (it‘s not even attractive for beginners) and Version Control (if you don‘t use Unity Version Control).
