The Chinese character for man (male and female) is 人 (ren)
In Chinese culture, ren (人) does not refer to the biological understanding of man. Rather, it refers to what a man ought to be – what makes a man a fully human person. One big difference between Western and Chinese philosophy is that in Western philosophy, the major question is “What is man?”, whereas in Chinese philosophy, the major question is “How to become one?” (为人)
And so, it is essential for a every single person to learn how to be a man (为人), so that he/she can become one (成人).
This is realised/fulfilled through his relations with others. Hence, the importance of ren (仁). The etymology is quite simple. It just means two (二) persons (人).
When two people can live in harmony with each other, only then can both fully realise what it means to be a man (二人为人).