The Guardian: the moral of King Kong is simpler still: "Don't pick a fight with nature."
Letters to an Unknown Audience: The message of Narnia is clear: Don't ask questions. Trust the first person you meet and stick with it. Raise your ill-begotten sword for it.
I haven't seen either, but I'm curious to what extent these morals are injected by the films' creators vs. viewers. I also think it would be an interesting thesis project to compile a list of morals as described by film critics over a few decades, correlate those morals to political party platforms with some sort of text similarity analysis, and then measure ticket sales against election results.