"人们认为成为白人很重要的原因是他们认为不成为黑人很重要。"

Simplified Meaning:

This quote is saying that the people who place high value on being white do so because they believe it's very undesirable to be black. It means that some people think being white is better because they look down on being black. This creates a situation where white people might feel superior just because they're not black. For example, in history, during the time of segregation in the United States, white people often had access to better schools, jobs, and neighborhoods because society unfairly treated black people as less important. The belief that being white was important was based on the negative treatment and stereotypes of black people. To apply this to our lives, we should try to stop thinking one race is better than another. Instead of lifting ourselves up by putting others down, we should treat everyone equally and with respect. By doing so, we create a fairer, kinder society for everyone.