It appears that the translation here frequently uses "man" in the generic sense as meaning "human being", but often also uses it in the sense of "adult male human being". The context should make it clear which one is meant. When there is talk of "man" and "woman", the text presumably means "adult male human being" and "adult female human being". When there is no such opposition, but instead, e.g., there is talk of the love between men, or the love of man for man, or the nature of man, the text is talking of "human beings" (not about homosexual love, say, or masculinity). The term "man-person" appears to be always used in the generic sense of "human person".
I am making these remarks without access to the Italian originals of these texts, so I am only guessing based on the context.