John, thank you for moving it to the appropriate location.
Upon your note about the axes, I created a new preset in-game that removed all axes assigned. After that, I navigated to a fresh plane, and was still encountering the 'ghost' input issues.
The cable I purchased connects to the DB9 port on the console, and USB 2.0 to the computer. On the computer under Device Manager, the input shows up under the COM-ports drop down menu, and is assigned to COM7, which I selected when the hardware checker popped up upon launching MSFS, after which it checked and gave me the okay for the yoke and throttle quadrant.
I didn't realize it until you noted, but I had BOTH HID and COM files in the FSUIPC folder, so I moved the HID files out. I uninstalled and reinstalled FSUIPC7 just in case, added the COM DLL files back in, launched MSFS, got the 'okay' for the same hardware, but was still receiving the same 'ghost' inputs without my own touch. I've seen notes throughout the documentation I've read (I tried to read every possible doc on the software before sending in the request on the forum) that there are some niche issues where the hardware requires 19200 bit speed rather than the standard 9600, and have tried changing that on the port settings (the Speed:xxxxx setting was not shown on the DLL file, so I assumed I could change it in Device Manager), but still experienced the same issues.
I attempted to use the PFC Hardware Calibration and Test GUI, but unless I'm missing something, nothing showed up on there and gave me no indication it recognized applicable hardware. I assumed that might've been maybe the program was designed for the USB/HID model of the console rather than the COM model.
I'm determined to get this hardware to work, and maybe the solution is just something simple that I never thought of. My next thought was maybe trying another cable that connects the console to the computer, but it seems to connect to the PC fine and recognized without an issue; I'm not sure if that could be a factor or not.
EDIT --
Here are the links to the cables I purchased for reference:
USB to DB9, https://www.amazon.com/gp/product/B0758B6MK6/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
DB15 (male) to DB15 (male), https://www.amazon.com/gp/product/B00O07653K/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1
Power Adapter, https://www.amazon.com/gp/product/B01GEA8PQA/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1