On a fundamental level, the 12 forms of the Chinese zodiac are related to animal worship.

Source: Tatoeba

The twelve animals of the Chinese zodiac come from eleven kinds of animals originating in nature, namely the rat, ox, tiger, rabbit, snake, horse, goat, monkey, rooster, dog and pig, as well as the legendary form of the dragon, and are used as a calendar.

Source: Tatoeba

Jiang Feng's servant hired the "Twelve Zodiacs" to kill him. They ambushed him and his wife Yuenu.

Source: Tatoeba

The reason the cat is not included in the 12 animals of the Chinese zodiac is very simple.

Source: Tatoeba

Jiang Feng escaped and afterwards Yuenu gave birth to two boys, but the 12 zodiacs had been lying in wait and ambushed them. Suddenly two princesses from Yihua Palace appeared. They made Yuenu kill herself, and shortly after, Jiang Feng committed suicide.

Source: Tatoeba