REAL SPOILER!
The fake Zulu did not kill real Zulu. Zulu went to hunt for yanyan. She wanted those fruits that helps with her hunger during pregnancy. She always eats non-stop during pregnancy. And the only way she starts eating normally is if she is given high grade food. These fruits in the forests are high grade fruits. And also some meat she wanted to eat.
Secondly, when Zulu was gathering & hunting for yanyan, he came across a violent black snake. They fought to death. When the fake Zulu (also named "Ming Luan") came by, Zulu was already dying. Zulu made ming Luan promise to take care of his wife (yanyan) & also protect her.
So fake Zulu (also known as ming luan) decided to humour the dying beastman's wish. Then he started liking Yanyan because her babies are able to have high traits (like power of water, wood etc). And many females are not able to guarantee babies who can inherit such traits.
Ming Luan is from the line of Phoenix. He is not the snake. He also wants babies from yanyan. And he thinks she can give him real Phoenix babies. And later on, she is able to give birth to such babies and much more to other fathers.
When yanyan gives birth to babies, she gets rewards from the system and she can also increase her superpower. She also gets all kinds of baby products from the babies

Y'all i cant get over Zulu TT is he dead? Or alive somehow? The poor guy didnt even get to see his kids,he was the only one who wasnt obsessed with kids and bro they just kicked him out of the story,and whats with this narrative of having kids but losing either the guy or kid?since this is a world where she can have multiple men,just let her have them ╥﹏╥