1. Leadership is an art and not a science.
The true answer is that it is both. Leaders tend to understand the artful grace of commanding a team but the metrics used to implement ideas and principles are grounded in science: observable & repeatable.
2. Leadership is inclusively a human endeavor.
It exists in order domains- pack of wolves & pride of lions. Elephants also have a very sophisticated matriarchal understanding of leadership. The Australian steel-blue sawfly have leaders that decide on group movements.