Past times, past lives. My previous physical lifetimes on Earth or energies with which I am in good contact or have clear memories of.
I am currently a consciousness temporarily living in the human body in the physical universe on the planet Earth... Partly.
I can explain these memories as the result of my mind working in the state of meditation, theta or REM sleep, hypnagogy, information or subconscious memories translated into conscious visions, where:
They use symbols to explain the state of the subconscious mind, they are a metaphor, a projection, a resonance. They show my experiences from birth until death, picked up with 5 standard senses. They will die after my physical death. Or:
They use symbols to explain the state of mind, not only mine, but also the collective human mind (Jungian archetypes, collective unconsciousness). So we already have an additional sense, non-local (not only private). See also: Morphogenetic field. Or:
The information comes from a different space or time from another person, that is, yet another additional sense. Telepathy, ESP, Akashic Records? Or:
The information comes from a wider consciousness that actually experienced it all, repeatedly incarnating as a living creature, incl. in the physical world, e.g. on Earth. I am now its next iteration = incarnation. By looking through the keyhole or the hole in the veil of oblivion, I have accessed these memories and clearly identify them as my own. Models of souls and incarnations, Consciousness souls spirits.