Actually, i would agree with you there. I think that is exactly the message behind this movie. Despite the good intentions of humans, we can be very harmful to the natural environment around us. I think in this movie, Ashitaka represents the typical helpful guy, who wants to help the environment, but also wants to help his fellow human beings. Either way, he's conflicted.
San represents the typical 'environmentalist/hippie', who embraces the natural environment and fights against her fellow humans in order to try and change things for the better and save the natural environment she obviously cares so much about.
Jigo represents the typical capitalist, who just wants to make money out of whatever is available. He doesn't care about the consequences, he just wants everything for himself and people he serves, so life will work out better for him in the short term.
Lady Ebashi is one of those people who is generally a good person, but gets caught up in life and makes mistakes, resulting in damage to the forest (in this case the environment)... She probably cares deep down, but knows that she has a lot of other things on her mind, which she has to take care of. All-in-all, she is easily led and will end up being used for the goals of others.