In China culture, snakes symbolize mystery and evil. Why does China traditional culture regard it as Teng?

In the traditional culture of China, the snake is not a symbol of mystery and evil, and many legendary Han ancestors are the embodiment of snakes. Liezi recorded "Buxi family, mother snail family, Shenlong family, Xia Houshi, snake face, cow head and tiger nose". In China mythology, dragons are mostly evolved from snakes, and mountain gods all carry snakes. This shows the position of snakes in the traditional culture of China.

As for why snakes are now a symbol of evil, most of them are similar to ladies, comrades and professors, and they have been destroyed by something.

Like the story of the farmer and the snake, the shadow of the cup bow snake, etc. Everybody talks too much, so pull the snake off the altar.