I don’t see you longer response here (moderated? it was kind a rant), but I did receive it in an email so I will try to quote parts and address some of your questions.
I Came to 3D CAD many years ago with a design background, but not so long ago that I can’t remember the frustration in dealing with a new environment. While I appreciate the level of hair pulling this can engender, seeking to understand WHY things are done the way they are, and HOW you can accomplish your goals, will be more productive than ranting about how Fusion has it wrong. Ask specific questions, and ask for help, before you condemn the program. There are reasons, generally very good ones, for why Fusion, including the UI, works the way it does. There are things that could be done better to help new users, and questions help identify some pain points. Working through some of the getting started tutorials, particularly if you have no previous CAD experience, will shorten the learning curve. Jumping into a specific design and expecting things to work the way 2D design applications do will create frustration.
It’s my experience that the biggest stumbling blocks for new users is failing to understand the distinction between components, faces, features, and bodies. I expect this is at the root of your copy-paste questions. Work on understanding this and many quirks will start to become clear.
I’m not sure what you are referring to specifically re non-standard UI, some menu items are in different spots than might be expected- I think this might be more a reflection of the cloud and eventually browser interface than anything else- but standard keyboard commands work within the bounds of maybe having to understand additional context to get the expected results. Nothing about those interface elements inherent to C programming, they are conventions of the Mac or Windows OS, adhered to with greater or lesser fidelity by developers.
Specific to some of the issues I had was first in importing a basic 2D design from CorelDraw that I saved into dxf and dxg extensions. Neither could be "inserted" (why it is not called imported also baffles me) properly, and I finally had to insert the drawing from an SVG save, which then somehow made it 10 times larger (not sure why).
re. import vs. insert, I think the general use in Fusion is that Import means getting an outside file into the Fusion environment, into a project, so it can be utilized in a Fusion design. Insert means to take a component and insert an instance of that component into a particular Fusion design. In many cases designers will reuse components in different designs. The terms are distinct, I suppose somewhat arbitrary, but I think clear when you understand the distinction.
re. Corel Draw importing, again, looking at the file here could help. DXF should import into Fusion just fine, as a sketch, but some particular designs, particularly if they use types of splines, will not be CAD friendly and may fail. That’s a case where looking at the file will probably yield an answer. Not all design applications will provide good data for CAD import. SVG is tolerant, but less useful in some ways on import.
I found a similar item part that I wanted to design as a 3D model, and was able to bring into Fusion 360. I had my 2d design, which I extruded easily, and made some changes. I wanted design and the imported item design and though it would be great to "select" a part from the 3D model, do a simple copy/paste, and bring the part into my drawing that way I don't have to design it by hand. Can't do it. Just doesn't. I can select the part, but no real way to copy. I RMB and click the move/copy but nowhere do I find a past and CRT+V (again simple C++ programming commands) will do nothing, so I'm guessing there is no paste, at least in my sketch view. I am in MODEL BTW.
I’m not clear here if you are trying to copy-paste into another Fusion drawing or some other application. Move/Copy is not the right command for this, that is for moving features, faces, bodies, or components depending on what you specify in the dialog. There is a distinct Copy command if you select something where that is an option, such as a component. If another Fusion drawing, I suspect the issue is in knowing what you are selecting to copy. Is it a face, a body, a component, and are you selecting it directly in the drawing or in the browser tree? All of these options can yield differing results. But yes, you can copy-paste components between Fusion designs. It's best to do that from the browser tree. If the component is something you want to reuse again or reference, it’s probably best to RMB on it in the browser tree and select “Save Copy As…”, then import into the 2nd design. If you are talking about copy-paste in reference to copying a sketch, that is not possible in the parametric/ history based environment but you can do it in the Direct Modeling environment. In the parametric environment sketches are much more tightly bound, of necessity. 
Similarly frustrating is the lack of being able to copy/paste simple items. My design required several holes. Easily found the hole selector and made a hole and adjusted the length of the hole so it goes through my part - easy. Wanted to copy/paste the hole 3 more times since I need a total of 4. Can't do it. Had to design each hole manually.
This is a difference between CAD and visual design programs. A hole is a feature that contains a lot of information. If you want to create more of any such feature, Fusion provides a specific tool- Pattern- to duplicate holes or other features while preserving the data integrity. There is no need to recreate individually. In the modeling environment and you want holes that are not in a regular pattern or regular sized, the best path might be to create what you want in a sketch and use extrude. You can pattern sketch elements as well. There are many ways to do things in Fusion, the best path will depend on your goals. But Fusion, nor any other CAD application, is not going to work from a UI perspective just like a 2D drawing or design application.

The direct modeling environment gives a somewhat greater degree of freedom in moving around elements freely- It’s where I usually develop ideas. You may find it easier to get started with.
Anyway, if it does post, I wanted to add that why is it when making a hole the program doesn't detect the thickness of the item you are making a hole into?
It does, if you tell it to- but that's just one option. The Hole dialog that comes up allows you to specify a simple through hole as one of the options. There are many different types of holes. If you specify an "extents" hole it knows to stop at the extent of the body, even if another body is adjacent. If you are fastening several items together or want to drill through several in the same location, a common issue, the "distance' option will locate the hole on different bodies or components.

I have several 2D designs in Corel that I want to bring to Fusion for the ONLY reason that I need to export files to someone with a CNC machine. I don't do this for a living (CAD design) so I am not going to invest hundreds of hours to locate copy/paste or other simple functions, but was hoping that it would not be such a steep curve in learning the program's functions.
Fusion is one of the easer applications to learn for someone wanting to do what you describe- get a precise model for CNC. Plenty of people here have picked it up rather quickly, and done amazing work. Rather than looking for the copy-paste command you are used to, ask here “how do I…” and include screenshots or files. I think you will find things start to make sense.
- Ron
Mostly Mac- currently M1 MacBook Pro