My mother-in-law dreamed that a female ghost with long hair in big red clothes jumped into the ancient well!

Mostly because of anxiety or stress. Of course, there are also cases where you are in a good mood and dream of some happy things. Scientifically speaking, it doesn't make any sense. There is no need to take them to heart. In particular, some illusory ghosts are nonsense and can be used for entertainment and divination. There is nothing wrong with it. I hope to adopt them.