A more thorough explanation:

Definition: Mankind refers to all human beings collectively.

Examples:

1. John is a man.
2. Mankind has made great advancements in technology.
3. Sarah is a kind and compassionate human being.
4. In medieval times, a vassal was a man who served a lord.

The examples illustrate that mankind refers to all human beings, regardless of gender or social status. The first example shows that man can refer to an adult male, but in the context of mankind, it includes both men and women. The second example highlights the collective achievements of humanity. The third example emphasizes the individuality of each human being. The fourth example shows the historical context of the term man as a feudal tenant.