Now, I'm looking at this from an evolutionary aspect, because this is a problem of adaptation.
I do believe that at some point, we may evolve into something that homo sapiens would consider perfect. The Neanderthals may consider us perfect, for we have permanent settlements. That may be what mattered to them. But we don't look at our permanent settlements in the same way. Actually, that's a bad example, and I should use one of the earlier human species, but I'm in a rush here.
Now, what matters to us is debatable. Some people feel it is the ability to sustain ourselves and our environment at the same time. Others, the ability to co-exist. But I feel that our evolutionary perfection is simple to describe. If we evolved from not using tools, to using tools, to making tools that can do 100% of the work for us, then the next step might as well be implanting tools into our biological systems to make life even easier. Metal hands and pacemakers evolve into biotic limbs. We would look at a cyborg and say that that is our perfection. A rural farmer in China would be amazed that such a being can do all his work, essentially for him. Alternatively, a rural farmer in China from 10,000 years ago would be amazed at a modern rural farmer in China, simply because of adaptation - the physiology of Tibetans and Chinese is particularly interesting, because it has changed noticeably over a long period of time to suit their environments better. But I'm getting off track.
Anyway, so perhaps this cyborg is our idea of perfection. But this cyborg will likely see new problems associated with it, and aspire to achieve something higher. So the answer would be that such perfection is unattainable to humanity as we know it, because humanity as we know it is not yet capable of getting there. And once we get there, what we consider perfect will have changed. So no species is completely capable of reaching its own perfection without evolving into a form that takes that perfection as granted.
