Why is it that in Japanese sentence one sees 男 or 女 with furigana that says ひと? Furigana is supposed to help clarify the meaning of a kanji character, but using ひと doesn't seem to help clarify anything. So what's the point of doing that?
I think one of the reason would be politeness, for example あの人知っている？ is more polite than あの女 or あの男 in the sense. And the latter has some sarcasm or contempt.
Using 人 with おとこ or おんな can be seen in manga or may be used in lyrics. My understanding of the difference between actual words and furigana is that furigana sometimes refer to colloquial form, while main words or kanjis are used for deeper meanings.
For your case, reading as ひと is for politeness, and using kanji 男 or 女 to clarify the meaning, sometimes you may see あんた as 貴方 or 貴女 (for females).
I have never seen 人 with おとこ or おんな for the furigana, but I've seen plenty of examples when the person would be saying the furigana, but the meaning was further clarified by the kanji used.
For example, in Deadman Wonderland, it quite often has the letters DW with the furigana ここ because the person said 'here' but was referring to the entire park.