I believe this is generally true, however, a state of discontent oftentimes serves as a necessary impetus to enable us to act to make life better for ourselves. I'd like your thoughts on when to want what you have and when to be discontent. Certainly an drooloing imbecile rolling in his own poo can be happy because he doesn't know discontent. To me, this is the real question. In my opinion, it is more difficult to answer this question than it is to spew trite phrases about happinesss.
Evolution means change.
I assume you attach special significance to drastic change that includes great improvements to cognitive ability. It is change to a form which can outreproduce others. To say that humans are the most evolved species is a misuse of the word evolution. This is preposterous. I could go on and on.