Chinese people are Chinese because they have lived and derived from China. That is similar to saying "Why are American people American?".

Because Chinese people are from China and that means that they will obviously have Chinese children.

Chinese refer to people from China or have ancestors whom originate from China. Asians are people who are from Asia. While Chinese are asians, asians are not necessarily Chinese.

No, Hawaiians are not Chinese. People from the Hawaiian Islands are called Hawaiians while people from China are Chinese. There might be people who live in Hawaii who are Chinese though.

Chinese people refer to themselves as "中国人" (Zhōngguó rén), which translates to "people of China" or "Chinese people" in English.