Common experience suggests a common cause, period. It doesn't suggest that the cause is supernatural.
For the mandela effect, no explanation is necessary beyond two explanations we know are true regardless:
- human brains are imperfect, and often fail in similar ways.
- human memory is very mutable. Hearing a different version of an event than what you experienced can cause your memory to reflect the retelling instead of the actual experience.
Well, your thinking style then can be used to dismiss about every paranormal, crypto, alien, Mandela Effect, etc. thing out there. Human brains and senses are imperfect is the answer.
And I agree, no doubt they are imperfect but after years of interest in these subjects I go a step further and analyze if in a few rarer cases a deeper explanation is not suggested and sometimes from the quantity, quality and consistency of the claims I think 'yes, a true mystery is suggested'.
Back to the Mandela Effect in particular, I do all the time recognize normal memory errors in myself and others. However there are a few examples where I think something more mysterious about reality is suggested. After all, the idea that the universe is one fixed thing that we all only observe may just be a working model that only works 99.9999...% of the time. Einsteinian physics may be true but Newtonian physics works perfectly fine for all our normal needs (but is not the ultimate truth).
I believe the universe is consciousness created and you see it as physically created. Our two views will agree on normal things still 99.999...% of the time.
I think the Mandela Effect may be saying to those who are ready, hey...this universe is not what we assume it to be, 'Broaden your minds'.
To go further with this discussion we would have to give up discussing this in generalities and get into the specific cases where I don't feel the conventional explanation is satisfying.