Animal nature
The imagery of animals other than humans serves in this essay as an imagery that Marcuse uses to illuminate human nature. Instead of seeing humans as essentially different than animals, Marcuse reminds the reader that humans are quite literally animals. This is the bottom layer of the cake that Marcuse is baking in this book. As animals, humans are locked in natural battles for power and sexual competence, and they have animal desires that govern their behavior.
Money and technology
On top of animal nature, there are the additional dynamics of money and technology. Money is a physical symbol of social or natural authority, because money represents desire fulfillment. A person with lots of money can easily impress attractive mates, which leads to a kind of sexual superiority (because of selection and Darwinistic survival of the fittest). Technology represents a way of making money, either by improving the methods of production, or by offering products that improve the Civilization's quality of life through luxury or utility.
Capitalism and "hard work" narratives
On top of these mechanisms, there is overlaid a narrative about hard work. By lying about money to poor people, rich people can ensure workers. The narrative is often that by working hard for one's employer, one can hope to become as they are, but the limitations of companies are often various management positions, while real money is being made by the business owners and stock holders, who are typically already wealthy to begin with. The narrative is a myth that ensures production. By working hard, one can afford to buy the products that business owners will sell them, so that they can compete with one another in a lower class.
Science as economic tool
Marcuse's treatment of science shows that science is often done with expressly monetary interests. To find science for science's sake is very rare compared to science for economy's sake. Many scientific companies are merely research and development companies helping business owners to come up with new products. This is concerning imagery, because it means that for the most part, capitalistic efforts guide the scientific progress of the species.
