The idea of a collective consciousness that is passed down through a priori and innate knowledge from generation to generation is essentially a form of Lamarckian evolution.
Lamarck famously suggested that a giraffe got its long neck because one giraffe was able to stretch its neck during its lifetime and then pass this trait onto its offspring.
If our ancestors were able to construct new personal memories in their lifetime, then impart these memories into their offspring through a collective consciousness (ancestral memories), then this would essentially be a variation of Lamarckian evolution.
As a variation of Lamarckian evolution, dream interpretations relying on the notion of a collective unconscious are vulnerable to the same criticisms as Lamarckian evolution. Of these there are many. For example, if a man loses his arm in an accident, his children are not born without an arm.
Changes acquired during a lifetime, be it physical or psychological, are not passed on to offspring. Only those present in genes can be passed on. Nobody would suggest that our memories can affect our genetic structure and allow us to pass on a collective unconsciousness to our offspring in that way.