[marcosdumay]

Because the question contains many common symptoms of a good programmer:

The author can easily read code from others, there is no implication of other people complaining about his code, and can program in several languages.

There are also stuff that commonly causes impostor syndrome up there:

Very general surface level knowledge, problems with interview questions, and difficulty on understanding "very basic OOP concepts".

The only thing pointing to a bad programmer is that "although my solution is more likely to be a complete mess", but it's thrown there without any context on problem difficulty, code size or environmental restrictions.

Any of the best programmers I have ever met could have written that same question if they got reasons to doubt themselves.