The existence of evil in our world has been debated for centuries and I will not pretend to offer any final thoughts on the subject.
But this short video from Pastor Wilson and two sermons from Genesis that I gave some years ago will provide a good Biblical foundation for approaching any discussion of this serious subject.
Understanding the sovereignty of God by Pastor Doug Wilson
A short video with several helpful analogies. https://www.christkirk.com/sermon/reformed-basics-sovereignty/
The Trees of the Garden : Does Man Have Free Will?
A sermon from Genesis with no audio but you can read this introduction with the provided text link to the .pdf file:
A Dragon in the Garden : Why Did Sin Enter God’s Good Creation?
A sermon from Genesis with audio & a text link https://www.sermonaudio.com/sermoninfo.asp?SID=929131052146