To ask what it means to be human means to ask why we exist at all.
We are contingent beings. Even in evolution, we could have evolved differently, so there would be no humans.
But if we are contingent (that is, not necessary), then it leads to the question of why we DO exist. Given that humans are contingent, it means that there must be a finality to this contingency. Things cannot be contingent ad infinitum. There must be a final thing that is the source of everything else. And, given that this source must be responsible for the rest of the continuation of the universe, it means it must be capable of creation, and doing so in a personal way to create beings with agency (which we are). So, we exist because of a source that is personal, that is responsible for the creation of everything else: God.
Now, given that God created us, whether by evolution or not, I do not believe God would create anything without a purpose. As such, what it means to be human is to have some inherent purpose. What might that be? Well, probably something to the effect of being thankful to our creator for creating us.
Now, without getting into a huge, controversial argument, I believe the story of the Gospel touches on the deepest longings of our hearts based on the above. That is because, in the Gospel, we find that God is not some distant creator, but personal to us. In fact, God became a man, the man Jesus Christ. His claims to deity are clear in scripture. But his claims mean nothing if they are not true. As such, we need to investigate the claim that Jesus said he is God. And one really good way to test Jesus' claims is to analyze an argument given by Dr. YoungHoon Kim, who has the highest recorded IQ in the world.
Here is his argument. Try it out and see if it fits.
In the end, if we owe a debt of gratitude to God for creating us, then our purpose is to glorify God, to give some teeth to our purpose as humans. To be human is to give glory to God, whether we are consciously aware of that or not.
Romans 1:18-23
"For God’s wrath is revealed from heaven against all godlessness and unrighteousness of people who by their unrighteousness suppress the truth, since what can be known about God is evident among them, because God has shown it to them. For his invisible attributes, that is, his eternal power and divine nature, have been clearly seen since the creation of the world, being understood through what he has made. As a result, people are without excuse. For though they knew God, they did not glorify him as God or show gratitude. Instead, their thinking became worthless, and their senseless hearts were darkened. Claiming to be wise, they became fools and exchanged the glory of the immortal God for images resembling mortal man, birds, four-footed animals, and reptiles."