Im curious about this, has anybody discovered the answer to this?

Ok so obviously god is not real. and neither is the soul or the afterlife or anything of that nature. Im curious is to what determines our species? For example: A lion, what makes it a lion, what does it have that we dont have? Could it have been human? Is it random? Or us, did we have to be humans or couldnt we be an animal or something? Does this make sense to you lol? Its hard to comprehend, they dont have any control over that do they?? Another question, how did life come to us? Like how did concious come into our bodies, like are we picked or something?