“If you crush a cockroach, you’re a hero. If you crush a beautiful butterfly, you’re a villain. Morals have aesthetic criteria.” - Nietzsche??
The aesthetic standard is captured within evolutionary game theory. Cockroaches are evolutionarily harmful to our species (spread disease); butterflies are evolutionarily helpful to our species (pollinate our fruit and vegetables without stinging us). Our evolved moral sentiments do not treat all life equally - they are biases to our benefit.