Taylor went through an unusual arc.
1) He started off being disillusioned with humanity. "There must be something out there better than man!"
2) He found someone who agreed with him-- the apes.
3) Now being hoist on his own loincloth, he inadvertently reversed himself by trying to defend humanity's cause. Hypocrisy, or just a reality check?
In any event, he took the position that man was still equal or superior to the apes.
4) He discovered he was wrong. He ended the first movie disillusioned with humanity again.
5) The second movie... well, the ending tells us that he was equally disillusioned with everyone. If we didn't know that already.
(Which is kind of amusing considering the number of illusions in the movie. )