"Why would a supposedly good, just, loving G-d allow so much suffering in the world?"
(I started answering and realised I was not talking on her level. Can you help?)
You are a bright nine year old. There are many things that you can understand, but your baby brother would not understand. For example, does your baby brother ever get a rash? I'm sure he does. So what happens when a baby has a rash? Mum applies cream to ease it. The poor little baby screams as his tender skin is stung by the ointment. But mum keeps going, ignoring the screams. As hard as it is for her to inflict pain on her baby, she does it, because she knows that it is for his good.
Imagine it would be possible to ask the baby how he feels about the situation. He would probably say, "I am being brutally tortured by the very person who is supposed to love me and care for me the most! My own mother has no mercy. She ignores my cries. Why is this happening?"
And there would be no answer anyone could offer. There is no way in the world we could explain to a baby that no, it is not torture, it is healing. Yes it is painful, but it is only being done in order to prevent pain and make you better. A baby simply can't understand anything beyond the pain he is experiencing.
We are all like that baby. In front of G-d, even the wisest and smartest person is like an infant. We look at the world and we see the suffering and we ask why. And no one can give us a satisfying answer. We can't understand, all we can do is cry from the pain. G-d is moved by our cries, it pains Him to see our pain. He understands us. We don't understand Him.
The gap between our minds and G-d's is even wider than the gap between a baby's mind and an adult's. The baby will one day reach adulthood, and he too will come to understand the ways of his parents. But we will never reach G-d. We cannot begin to understand G-d's ways.
But the baby still loves his mum, even though he doesn't understand her actions. So too we need not understand G-d to love Him. Somehow, all the suffering in the world is a healing, and every painful experience is there to teach and to fix. Why does it have to be this way? G-d knows. We don't.