You might be right there,  生人 and 陌生人 are both unfamiliar person / stranger. I was just browsing. I suppose that the literary (or literal) meaning can be somewhat meaningless in the vernacular.

I mean, if you think of the default of not-knowing a person before becoming familiar with them, they are a stranger, or, a living person. Just that we don't say, 'hi living person!'

ideasfromtheedge

Learn Chinese with Sensei #2: 自由人

cryotosensei

Thanks for researching so deeply!

I doubt that we say 生人 because 陌生人 (stranger) has the character 生.

Let me teach you an idiom: 人山人海 (literal: person mountain person sea). It refers to a crowded place 