How to Use Analogy in a Hyperbole Joke

We need to compare two disparate things and then map the tropes, phrases, and common themes of one onto the other without referencing the first. So what's an analogy for human beings being selfish? I'm going to stick to the broader subtext here of the entire human race and not just me. What are words that are similar to the word selfish? Self-life. There might be something in there. Human's selflessness leads to short human shelf-life-ness. Oof, that's very clunky but it counts. We've got 11. Now to use analogy, which we already did in one of our hyperbole jokes, but we're going to try to do a