I have read that rebirth in the apāyās occurs as a result of akusala kamma. Does this operate for humans only? Why if beings remain in the lower realms and the realms of form and formless until the kamma that led them there is extinguished, doesn’t it work the same with humans? Can’t the karmic energy that brought us to human bhava extinguish by itself? What if our kamma is neutral – not defined enough to cause a higher or lower rebirth? Do us keep being reborn over and over again as humans?
Please take the time and read some posts that seem to be relevant to your questions.
– I answered your questions on gandhabba before seeing these questions. I think you should learn about the laws of kamma before getting into issues relating to gandhabba. Those are more complex issues.
– So, my advice is to focus on the above section first.