I have actually alsways viewed it, as a show that has a lot of deeper meaning. What south park does, is they make fun of every side of the story. Everyone gets a piece, wether they like it or not. Thats the fun and beauty of their critiques. And actually they have a way of saying it how it is, without packing it in. Wether you agree or not is irrelevant. As they always take up current debates, it is meant to provoke you, it is meant to make you question things. and they do it in a funny satirical way.
As far as the man bear pig thing. Yes. They thought it was a hoax. Many years later they resaerched it, and realised they made a mistake.
They have dedicated 2 or more episodes as an apology to Al Gore, for not believing him and making fun of him. Whiiiile making fun of him again. But thats how south park is