Kinda. What you’re referring to is “decompilation”, which is the process of taking the output of a compiler and trying to reverse-engineer the code that produced it. But decompiled code is really hard to read and modify, because it isn’t what humans wrote, it’s what the compiler translated it into, and that can have some unexpected changes than are mostly irreversible. And, since it’s closed source, if you somehow manage to make a change, you can’t re-release it – you don’t have the license to do so.

With open source, you see the same code as the maintainers, so it has the high-level programming concepts and good variable names, and you have permissions to fork and release your own version.