Do you not have any idea of how symbolism works?
Revelation 17:3 So he carried me away in the spirit into the wilderness: and I saw a woman sit upon a scarlet coloured beast, full of names of blasphemy, having seven heads and ten horns. 4 And the woman was arrayed in purple and scarlet colour, and decked with gold and precious stones and pearls, having a golden cup in her hand full of abominations and filthiness of her fornication: 5 And upon her forehead was a name written, Mystery, Babylon The Great, The Mother Of Harlots And Abominations Of The Earth. 6 And I saw the woman drunken with the blood of the saints, and with the blood of the martyrs of Jesus: and when I saw her, I wondered with great admiration.
So, when this passage refers to "her", that means it's referring to a person? Using the logic you use regarding the reference to "him" in Revelation 13, that is what you would have to conclude. But, of course, the passage is not referring to a person. So, your argument that references to the beast as "him" in Revelation 13 mean that the beast is a person is not valid. Symbolic entities can be referred to as "him" or "her" without referring to human beings.