If you look at our history over the last 70,000 years actually we are trying to rule only, make ourselves dominant over other species all around the world. Since Sapiens decided to leave their East African homeland for the second time, around 70,000 years ago, they virtually made other human species extinct. Modern human genes hardly have any traces of our Homo neanderthalensis or rudolfensis DNA. Around 45,000 years ago, all big creatures of Australia started to become extinct. It particularly coincides with exactly the same time when the first Afro-Asian human set foot on this continent. Around 800 years ago, when the first Maoris arrived, New Zealand lost all its major species and sixty percent of its birds. This list goes longer and longer, throughout history, from the days of early apes to till date. Most of the large animals that survived the onslaught of our ancestors disappeared or are almost on the verge of being extinct today, be it Tasmanian tigers, American cape buffalos or Asian/Siberian Tigers. Our forefathers were explorers but they were certainly not naturalists.
It is not the curiosity that makes us much different from other species. It is our better cognitive skills that made the difference. It is the very forbidden fruit that our ancestors swallowed around 70,000 years back. Despite being much smaller in size than their Eurasian neighbors or say, the arctic mammoths, our ancestors beat them out of this planet because of their better organizational skill, better coordination between bands.
As for the original question, whether Human is a purpose or mean to a purpose, let see how we defined our purposes so far. We mark our civilizational success keeping in mind our agricultural revolution, domestication of animals, organized societies, large cities, back to back Industrial and political revolution few centuries ago. But still we could not get rid of our hunter gatherer instinct; Our subconscious ego has not changed at all as it could not outpace the post cognitive revolution changes in human societies around the world. We are still animals deep inside our heart. With each and every revolution our ancestors longed for better lives for their successors but that goal remained forever elusive. It is my opinion that, being an accidental product of natural selection just like other organisms we have no real purpose other than only to become extinct (like many others who might laugh at us from heaven if there is any) from this very earth; Be it from some ecological catastrophes, or self inflicted irreversible damages.