Our past and future lives are determined by several factors, from what is called Karma here, to our own beliefs as well as our own determination. I have determined - or chosen - to be specific people for the last few thousands of years for the purpose of teaching Mankind what I am teaching, and to gain the necessary knowledge and insight to perfect my teachings.
Long time ago, other beings came to Earth and trapped Earth beings and enslaved them, implemented mind program systems, soul capture, reincarnation, and systems to keep Mankind work as slaves, not knowing their true Origins or Selves. You may call these beings Anunnaki, Aliens, False Gods, and so on if you want, and their home Nibiru, Hell, or even Heaven.
After they left, the System was still in place, and humankind still suffer from Amnesia and are victims of the Mind Control program and Reincarnation and Amnesia effects. Others are currently abusing this system for their own agendas.
The System is made to deceive people from the truth and lead them to lower astral realms after death and keep them within the trap system and reincarnation and to return as slaves and prisoners of Earth.
What went wrong for the creators of the Trap System was that we discovered that we were in a prison system as slaves, a world created by a greedy and ruthless god. Ths symbolism of Eden, Adam and Eve, the Snake and the Tree symbolises Human Kind waking up from the Illusion, by experiencing their divine self through kundalinin raising (The snake, also called Raising the Kundalini Snake), where the Tree of Knowledge opened itself (the Tree of Life being that of the Kabbalah). The Apple, was the Fruit of Knowledge, which indeed explains that all they did was to discover their true being, see the false from the real, good from evil, and so on which enabled them to further develop themselves spiritually and try rise above the Prison World they were put within. Of course, them gaining this Knowledge and understanding is the whole reason the God of the Bible got so furious. A loving God would obviously have let them be in their True spiritual state of being with all knowledge from the very beginning and not trap their spirits in physical limited bodies that suffer from the laws of reincarnation, amnesia, and so on.
Polarity exist on lower planes of Existence due to the Source splitting itself and making new energies form that in turn became new creators of different polarities, and this continued down all the way to the physical world, and is why we have Good and Evil and so on. The Source, True God, is Oneness and neither Good or Evil can exist as they are one and the same there, it is Balance and Harmony. Here these polarities are split up within different entities and individuals, some having more of one polarity than the other.
Reincarnation and physical existence has nothing to do with learning, and Earth is not a "School" but a "Prison", it was forced upon us, if we werehere to learn it would only be logical that we remembered our past lives so we would not do the same mistakes over and over, nor progress spiritually. Many people are still on the same level mentally and spiritually as thousands of years ago because of this. It also causes other unwanted effects such as lost souls after death, confusion, suffering, problems, all things a true god of love would not even consider putting our true spiritual infinite selves through.
We are eternal beings, with infinite life, and when we free ourselves from physical imprisonment we can continue our path towards our true spiritual development as our true spiritual beings with All knowledge about ourselves and our past and full intact memories so we can properly progress and advance on the spiritual planes of existence..
But I too have fallen by the trap system, and had "lower lives" such as farmers and even drug addicts. One of the problems with reincarnation is the memory-blockage, and erasure and resulting amnesia. Thus, it is rare for even advanced beings to remember who they are and it takes time for some memories to surface enough for that being to start realizing whom he is, or at least enough to start persuing a spiritual path that can lead to more of his memories coming back until he eventually finds and remembers his true spiritual essence and the way in which to remember all.
So, that means there are spiritual systems of Earth that are useful for such purposes but one should be aware of the mentioned traps and deceit built into the whole System, even advanced beings have fallen back to low states of being and are now trapped here without knowledge of why they are here or from where they came. You could be one of them.
And in the end, all of you are advanced spiritual beings, souls coming from the Highest Source, you are just different fragments of the One Source making yourself experiencing individuality and different stages of "development".