I've had some flickers of memory of a past becoming, I was an ascetic yogi in India. Just a glimmer I experienced several decades ago. I feel there was some other memory, that eludes me.
I came across the traditional ideas of reincarnation via studying the eastern philosophy; the late yogi Chiranjiva once said "when a man dies, he becomes one with existence, without loosing an individual point of view". My intuition leads me to accept the concept of reincarnation, as presented in the ancient philosophical views.
The Bhagavad Gita presents the view that humans may get time in out-of-the-body "heaven", but they are surprised when they begin falling back to human birth, once their "brownie points" are used up.
As to animal vs human re-birth, I've been under the impression that the way a person could be re-born as an animal, would generally be because they have become more animalistic and lower-natured in their previous human form.
The Katha Upanishad presents some interesting viewpoints that are apropos here.
ymmv!
Johnpipe
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He who sees all beings in the Self, and the Self in all beings, hates none -- Isha Upanishad
Bom Shankar Bholenath! I do not "have a syndrome", nor do I "have a disorder," I am a "Natural Born Scholar!"