It has the meaning of living person, and is also grammatically correct, but with dialects, you just say things a certain way. 生人 might be correct in written form, but we do not say that when speaking the language, at least not when speaking Madarin or Cantonese. I'm fluent in both dialects, so I know. But different dialects say things differently, so there might be a dialect that call "living person" 生人; however, I only know Mandarin and Cantonese, so I don't know which dialect would say that.