Shi Chui and the others were demons, but they were very different from the demons that Zhao Hai knew. Shi Chui and Hong Hua (originally da Hua, now with a different name) were better off. They were originally plant soldiers and had followed their Masters everywhere, so they had some understanding of human relationships.
However, things like iron thread grass and iron spine tree were far from that. Other than following Zhao Hai for a period of time, they had never come into contact with humans. They did not understand the way humans lived.
However, if they wanted to go further on the path of cultivation in the future, they would have to understand more about humans and adapt to human life.
Why did the monster race have to transform when they were strong enough? The main reason was that the human body was more suitable for cultivation, and human potential was the greatest.
