The Problem of Evil

"could always do more good" is not a deliverable- stop using it to complain about the good we actually have. Actual good is objectively better.

"God should eliminate evil."
What if He started with you?

At what age should children stop being indestructible?

"Why didn't God just make man free, in heaven, and everything perfect from the start?"
Only my opinion, but I think this isn't that hard to understand:
Suppose you come to doubt the only source of information you previously trusted when there's something you can't fully understand.
In other words, how can a being (man) with limited understanding come to trust the God with infinite understanding when there are inevitably things man won't understand completely? So then, we learn to trust by experiencing the inferiority of other ways.

"What would praying do? I mean there are children dying of cancer today whose parents are praying too and it’s not working."
rest stop or destination?
"rest stop, at least I know it's real"
You asked for the world with cancer and complain you got it.
The world astray from God *is* bad, and *not* the destination. Jesus raised the dead - they didn't stay *here* forever.

May I recommend:
Paul Copan, Is God a Moral Monster?
Clay Jones, Why Does God Allow Evil?: Compelling Answers for Life’s Toughest Questions