@Anonymous wrote:
... Just saying it might be worth pointing Noobs at the material about BORN. Although I had been involved in software development in CAD/CAM in the early 1980s I don't recall that term from back then.
A lot of the questions you are asking in conjunction with your prior experience in CAD/CAM lead me to believe that you have not yet fully taken advantage of the learning materials that are provided by Autodesk.
Many of them can be reached directly from within Fusion 360.
The "Self-Paced Learning" leads to a number of full courses covering the full breadth of Fusion 360.

Having said that, with your experience you fall somewhere between the cracks.
You are not completely new to CAD/CAM but that experience dates back to a time way before parametric CAD software became mainstream.
To address some of your questions, a component in Fusion 360 is a container that contains all, or at least most of the objects that are used to create the geometry (bodies) and functionality (joints) of that component.
A body is only a single contiguous bit of geometry.
Each Fusion 360 file already is a component. As such if you only want to create a single part, perhaps for 3D printing or machining, you don't need to create another component as that would add an unneeded structural layer.
If you want to create an assembly of components in a single file, it might be a good idea to start the design by creating a component. That is described in Fusion 360 R.U.L.E #1.
The original intend for inventing that rule was to help beginners over the first hurdles. It was never meant to adhere to religiously. Most folks that reference it don't read the first part of the first sentence "When in doubt ...". Most also ignore the second part listing perfectly valid alternative workflows.
IIRC you imported the sktches/.csv data into the top level.
If those sketches were meant specifically to create geometry for a single component, then the best course of action would have been to create a new component and then drag hat sketch into that component.
If you forget to do that and create the component after you have created geometry, it might not be too late.
Dragging the sketch into the new component might pull the bodies created from that sketch with it into the component.
By default components are "floating" in FUiosn 360. So the first course of action should be to determine what your stationary/reference component is and then lock it into space by grounding it or creating an as-built rigid joint between it and the top-level origin.
All other components will then be assembled using the joints in the Assemble menu. A "normal" mechanical assembly should not contain any (body) move, align, or position-capture features.