There is nothing that you said. The rain said they didn't like it because of plagiarism.
That's what Rain said, yes. But that's not why people here on the forum don't like it.
This question of the protagonist and how we connect with him, is something that we use as a device to run a hand over the heads of the guys.
I have no idea what you are trying to say here (are you using an expression from another language maybe?). 'Run a hand over the heads of the guys'? Do you mean petting them? Pleasing them? Reading their minds? Copying them? Misleading them?
I first thought it meant kissing up to someone, but apparently not? Please try explaining again in different words.
If it were just because of the protagonist I would not see any problems after all there are many good manga that people don't like the protagonist.
Yeah, but those manga usually have something else to offer. Like a good mystery. Or humour. Or interesting side characters.
This series (so far) only has the MC and his internal conflict, so if you're not into that, there's not much left to enjoy.
But the real reason is silly, when we see that there are manga that address issues worse than plagiarism and nobody says anything, they accept it calmly.
Yeah, I'm just going to repeat myself here:
Just having crimes in your manga isn't a problem (obviously), but if you want people to connect with the story, the way it is portrayed matters. A lot.