The Zerg campaign uses the word “essence” in almost every conversation. There are lots of interesting questions about “essence,” such as questions in constructivism and the challenge of natural kinds. Setting aside such puzzles, we can see that the Zerg obsession with essence is in the context of furthering power through connection and infestation. Unlike the Terran approach of controlling systems of power, the Zerg connect with power and weave some element of that power into themselves. They break down the barriers of distinction between themselves and the other thing. They seek to permeate and be permeated by those things around them, and are drawn to power to be permeated by it and integrate it into themselves; their infestation is presence, or “Being” in a sense Heidegger might approve of.
Even the essential game mechanic of the Zerg, “Creep,” illustrates the role of connection for this race. A growing, living carpet is the foundation of all Zerg bases and provides bonuses to Zerg units. Everything about the Zerg is a matter of connection: their hive mind, their sprawling, organic physical connection, and even the origin of all units from the same structure are all directed towards breaking down distinctions between beings into a single whole.
A lot of this is rightly alien to humans, if only because we don’t cover ourselves, each other, and our world in mucus. However, we do form a less tangible sort of organic carpet that connects us to everyone around us, which we call our culture. This living background also directs how we connect to power, each other, and ourselves.