"He wrote a movie to scare people."
Cameron has never written a movie to scare people. He writes movies about Love straight up with everything else being backdrop.
"When did I say that?"
You are implying it by declaring Ripley as the soul (mispelling intended) focus.
"Hicks and Newt are not developed characters."
Hicks is less developed than Newt, though you see Cameron wanting to develop him more in the special edition after he cuts the horribly sappy dialogue between Hicks and Ripley before she goes out to rescue Newt but this is unnecessary because Hicks is not the catalyst. Newt is the most developed character second to Ripley because she is the catalyst for Ripley facing her fear which sets the stage for the message of the movie which is, the most powerful weapon against your ultimate nightmare is Love (not guns, bravado, etc). And that's a message aimed at everyone kids included.