First off: I am realy happy that people like you, are helping people like me, who are learning the basics of ( in ths case) godot.
But I am not bothered by the way godot is set up. I like it and it's the reason I stepped overt
to this game-engine.
My 'confusion' is not hard to understand; I say so it in my question: in my head are floating a dozen different concepts of how 'machine-languages' put pictures on screen.
And godot just happens to that different.
And the 'why' is not why godot does it this or that way, it's about why one needs a recturerect to show an image.
Knowing a bit more; I would explain it like this: A node2D is like an empty canvas.
For it to show something, that something needs shape and position, provided by a recturerect; and color in the form of a texture. If you want to show an image, you then have to place its texture in the texturerect.
(I would no be surprised if 'the above' isn't even correct, but it's the thought that counts)
And how to code that, or to do in in the editor, I can figure out by myself... or ask once more. ha!
This is not a be be critical; just telling why I asked the question, the way I did.
It reminds me someway of the story of the boy and the fisherman. The boy asked why he is fishing near the bridge. The fisherman tells a sob-story about his wife and hungry children.
But the boy just wanted to know why near the bridge was better.
So he shouts: aren't that your wife and children I see in that steer-less boat in the distance?
The fisherman drops all and runs of towards the horizon. The boy picks up the rod and hat and makes himself comfortable on the riverbank.