Yea horror wasn't the right choice of words. He described his The Sixth Sense movie as a psychological thriller, which I guess is apt, though it was so much more than that.
As for Signs, while it was definitely a story about the personal demons and interpersonal relationships within a small family, I wouldn't say aliens had nothing to do with it whatsoever. Actually, the threat of the invasion featured prominently. I wouldn't simply describe it as a movie about an alien invasion though, but I don't think think there was anything incorrect about my sentence "In Signs, the alien invasion was told from the point of view of a small town farm owning family.", in context of my critique of Shayamalalalan's (that's a made up name, so I can make fun of it) directing of Lady.
I saw some bits of Signs on TV a few weeks ago, and I really did like that birthday home video thing. It felt realistic and was hair raising.
But yea, the movie isn't simply about the alien invasion, which is why I don't get the complaints that:
...It was illogical for aliens vulnerable to water to invade a planet covered in it. It wasn't the sort of movie to address the science of that issue. I am sure they could have presented any excuse like the aliens were desperate, suicidal etc. I just never felt the need to know because it wasn't that sort of movie.