Do I need to learn a 3D modeling software?

So, I'm trying to print some older models from thingiverse and I have discovered that basically all the files I want to print have glaring flaws in them.

Internal free floating structures, connector pieces and holes that are the exact same size... So on and so forth...

Do I need to learn a software like CAD or Blender to fix these? I seem to be able to do some basic stuff in Orca Slicer but it honestly seems like as much of a pain to modify the parts there as it would be to use a real software.

Is there one that's easier? I think I messed around with SketchUp once upon a time.

I am worried this feels like opening a can of worms just so that I can make a thing that already exists in a dozen forms better.