How can I identify simile in The Prophet of Zongo Street?

The Prophet of Zongo Street is a collection of short stories by Ghanaian author Mohammed Naseehu Ali. In the eponymous story, there are a number of similes. I have quoted and explained two of the similes below.
On the fifth page of the story, the narrator and his friends are described as looking at one another "like a flock of sheep in a small, tight pen." At this point in the story, the narrator has just asked Kumi if he is happy. Kumi then proceeds to asks the boys, including the narrator, to think about why nobody has ever attained a state of permanent happiness. The simile comparing the boys to sheep implies that the boys are a little embarrassed. This is a conversation a bit too serious for them. The simile also suggests how they feel trapped, as if in a "small, tight pen." Kumi has, from their perspective, trapped them with a question for which they have no answer.
Later in the story, after Kumi has not been seen for six weeks, "piercing noises" are heard coming from his house. Rumors begin to circulate that the noises are made by the ghost of a man buried beneath the house. The noises are said to sound "like the voices of a thousand people, all of them chanting, screaming, and shrieking." This simile creates an ominous atmosphere, and emphasizes the loudness of the noises by comparing them to the sounds made by "a thousand people."