This is an extremely important matter - at least for modern people. I mean, questions about why 'people' suffer so much - the demand for explanations as to why some other-person, or group, have suffered - the demand that this be explained in terms of God's goodness and power...
Failure to provide 'adequate' answers to this demand (and, for reasons I will explain, all answers are inadequate) is generally regarded as a sufficient reason (or, at least, an acceptable excuse) for abandoning Christianity (and then - typically - embracing a favourite, usually sexual, sin).
Each man's life is unique - the life trajectory is unique - because each Man's soul was different from the beginning, and to this different original constitution are added differences in experience, and differences in what has been learned.
So each person needs different things from his experience of mortal life. We chose our mortal lives and were placed in a specific situation and our life is divinely shaped - so that our needs for learning experiences are met.
However, it is up-to each-of-us to learn from the experiences. If we don't they may be repeated, and may be made starker and harsher - but in the end, we may chose not to learn (It happens. A lot.)
Mortal life is about supplying these specific needs. Mortal life is about learning; it is Not about providing the happiest experience, nor the least suffering. Mortal life is mostly about providing what we personally - and each is different - most need for the eternity of post-mortal resurrected life.
But these needs depend on the unique contours and destiny of each soul. We have distinct pasts, and we are not being prepared for identical futures - instead each person is being encourages to make the most of his own special attributes.
In Heaven there are no professions; each niche is unique. Or rather, each unique person develops an unique role in the world of creation. Each person is irreplaceable. If he chooses Heaven he brings something nobody else could; if he rejects Heaven then it leaves a gap that never can be filled.
So, when we suffer in our own lives; we can potentially know the meaning of this suffering - we can know this directly because we know our-selves and God will answer our questions (if the question is answerable, and if we actually ask it of God).
The proper question has the general form: "What does this particular experience mean in the context of my eternal life?" The answer will have the general form of explaining what it is that we need to learn from that experience.
We can know this, but no other. But we cannot know why others suffer. There is no general answer to why somebody or some group suffers. There are as many answers as there are specific people, and specific instances; and we do not know enough to ask the right questions; and even if we did, it is none of our business - it is a matter between God and that other person; because the suffering is in context of his life, not ours.
Mortal life is a very serious business - otherwise it would not happen at all. The necessary experience of a particular mortal life may come very early in life (after all, most people have died in the womb or around birth); or it may come at the last moment (perhaps after several previous failures to learn from earlier experiences, or perhaps because that 'imminent death' context was exactly what we needed to learn-from).
None of the above can be proved, as a generalisation, by evidence. Because the argument is that the necessary evidence is not available to us.
But we can know about our-selves, and that direct knowledge can tell us about the nature, power and personal love of God.
And that is the answer.
Note added: To put matters in reverse: If we do not understand the reason for our own suffering - then we cannot understand the reason for another person's suffering. This applies both for suffering in general, and for specific sufferings; it applies for ourselves as individuals, and for the groups of which we are members. If we really want to understand the meaning and purpose of suffering; we must start at home.