Examples of Metonymy. Metonymy is the use of a linked term to stand in for an object or concept. ... Sometimes metonymy is chosen because it's a well-known characteristic of the concept. A famous example is, "The pen is mightier than the sword," from Edward Bulwer Lytton's play Richelieu.
I think sloths are like us humans
It would be imagery because the excerpt is very descriptive.