[ The random mention of sea monsters is a bit strange, but frankly, Aziraphale just isn't smart enough to work that one out on his own. Not without a lot of time to think it over - and certainly not when the young man is moving on to the next question. ]

Why, yes, nearly everyone in London is a human as far as I'm aware. Apart from myself, and my demonic friend Crowley, of course. Most other angels and demons don't spend much time on Earth.