There are some universal symbols that can be used to gain inward insight and make aspects of the future knowable.
While many aspects of a dream are very subjective, there are some symbols that conjure up similar feelings in every individual and culture they occur in. Dream atlases, which document dreams people have as well as the feelings they associate with the dreams, show that certain symbols almost universally represent the same thing. For example, children in dreams represent new ideas for creative expression. If the child in the dream is 5 years old, it might refer to an idea you have been thinking about for around 5 years. Water represents a pure form of happiness. Houses can also represent your life.  A dream app that catalogues dreams reported a vast uptick during school exam season in the number of students reporting dreams in which they were unable to find their school classrooms. This illustrates how a shared emotion such as exam anxiety, can lead many people to share the same dream. As such, we can conclude that there are shared dream symbols.
There is absolutely no science behind any of these assertions. The idea that we have a shared dream vocabulary is not supported in science. We have not yet been able to link a particular feature of any dream with a particular emotion. The fact that many people dream about similar things does not tell us anything about what that object means. We are ascribing universal meaning to objects in dreams without a shred of credible evidence for doing so. The idea that these dreams may be able to predict any aspect of the future is laughable. There has been no science to prove this either. Any evidence in which someone accurately predicted the future based on a dream is purely anecdotal and most likely coincidental.
[P1] There are universal dream symbols that have shared meaning when they occur. [P2] These can be used to provide accurate, objective dream interpretations.
[Rejecting P1] There is no empirical scientific evidence to suggest that any symbol has a universal meaning in dreams. [Rejectin P2] Therefore, any dream interpretation is nothing more than speculation.