Final answer:
The phrase 'Left by men-slugs and human serpentry' is a metaphor for negative human traits, equating repulsive behaviors to the characteristics of slugs and serpents.
Step-by-step explanation:
The phrase 'Left by men-slugs and human serpentry' uses vivid figurative language, likely to describe deeply negative human characteristics or behaviors. After analyzing the given context and similar texts, it's clear that the phrase is not meant to describe literal slugs or serpents, neither does it reference specific historical figures or mythical creatures directly. Instead, it is a metaphor for negative human traits, equating certain behaviors to those of creatures that may evoke feelings of repulsion or distrust. The texts provided allude to the degradation of humanity through various forms, whether it is the cruel behavior highlighted in Cavendish's poem or the dehumanizing aspects of slavery. These comparisons, like the phrase in question, serve to criticize and reflect upon humanity's darker sides through the use of animalistic or monstrous imagery.