You are completely wrong in part of your argument. To quote you:
"This is completely wrong. Source code is perfectly understandable to computers. Indeed, there are programs called interpreters that allow computers to directly execute programs stored in source code form."
The fact that the computer needs an additional interpreter to understand the source code means that the computer does not understand the source code at all. By your logic I can be accused understanding Japanese if there happens to be a person standing next to me who can interpret for me. I cannot understand a word of Japanese and unless I have the internal ability to do so you cannot rightfully accuse me of that capability.