I am glad that Embodied asked this question. I found that bullet #12 of that post had an error that went without catching my eye since it was originally written probably in 2014. I just revised it. Scientists have it wrong with the “Big Bang theory”.
Regarding the questions:
a) “STILL IF A HUMAN HAS GOOD KAMMA SEEDS HE SHOULD REBORN AS HUMAN, NOT AS AN ANIMAL ?”
Not necessarily. We all have innumerable good and bad kamma seeds.
– It depends on which kamma seed is most potent: a good kamma seed leading to a human birth or a bad kamma seed leading to an animal birth.
– Also, good kamma seeds have many varieties: human, deva, brahma, etc and an innumerable varieties within those. For example, a human can be born healthy, handicapped, rich, poor, etc.
– Similarly, bad kamma seeds have many main varieties: animal, preta, vinipata asura, niraya beings, etc, and an innumerable varieties within those.
And each person may have innumerable kamma seeds both good and bad. Which one comes to the front depends on many factors. This is why the Buddha said kamma is one of those things that can never be fully grasped by anyone other than a Buddha.
– But the important fact is that if one is a Sotapanna, no bad kamma seed leading to a birth in lower realms will not be effective. In effect, they lose potency when one attains the Sotapanna stage.
b) There no traceable “beginning” to the pancakkhandha. We have to remember that each living being (whether human, deva, preta, any animal including amoeba) has its own pancakkhandha. Pancakkhandha is infinite for a given living being. Panca upadanakkhandha is a tiny, tiny fraction of it.