Before the implementation of the Imperial Examination in history, what official selection systems did China have?

Before the Qin dynasty, it was all hereditary.

Qin Dynasty: Appointed by Jue Di according to his military achievements.

Han dynasty: the procuratorial system selected talents from all over the country (basically hearsay)

During the Three Kingdoms and the Jin Dynasty: Nine-class Zheng Zhi System (basically in origin)

Sui Dynasty: The imperial examination system was abolished.

The imperial examination was established when Wu Zetian perfected the imperial examination system in the Tang Dynasty.