The hadith pictures a hole from which a person has already been stung. Returning in the same careless way would repeat the danger. This is a vivid analogy: a concrete image conveys a broader habit of intelligent caution.
Example 1: A student fails after repeatedly studying too late. Rather than repeat the same routine, they improve their preparation plan.
Example 2: Someone loses money to a fraudulent online offer. Before paying again, they verify the seller and the details.
In جُحْرٍ وَاحِدٍ, وَاحِدٍ describes the noun and agrees with it in the genitive case.