I think the problem of God and suffering goes deeper than just our ignorance of God's purposes.  Regardless of God's purposes, when you are an ethical God, the end never justifies the means, and if you are all powerful, then this God can accomplish his ends regardless, and does not need to resort to unethical things such as permitting suffering.

Rebirth (the Buddhist and Hindu word for what in the West is often called "reincarnation") would not, it seems to me, provide a way to grow unless there is good memory of past lives, which manifestly there is not.  Both Hindus and Buddhists agree it is a manifestation of the immortality of the life spirit, but they disagree on whether it is a form of immortality of the person.  Hindus, if I understand correctly, do, but Buddhists do not.  The process of Samsara (birth, life, death, rebirth, over and over) is seen by Buddhists as at best a trap wherein one is condemned by the natural force known as karma combined with our instinctual desire to live (animal grasping onto life), to be born over and over in one life after another, sometimes for the better, sometimes not, but all including large dollops of suffering.

The idea in Theravada Buddhism, though, is that the new baby is not the person who died, but just the life spirit, with few if any past memories, just the karmic status.  The new baby has its own genes and its own life experiences and is in fact a new person.  When one dies one is dead, nothing lasts forever.

I don't know and don't venture to guess whether this view reflects reality or not (at best any such picture could only be a reflection).  Instead, while I can see where evolution fits within such a picture much better than the Wester theist ideas, I can also see where it is more likely these ideas of afterlife derive from wishful thinking and the reality is much more bleak and we live in a universe that happened entirely by natural processes without any purpose.  The first goal of wisdom is to learn to accept the universe as we find it, not as we would like it to be.