Great questions. The whole topic is very difficult and perplexing, as you point out. Some time ago, following another article on a similar theme, Jack Preston King responded that, before even beginning to discuss this, one should define what one means by evil. You are now making the same demand.

My working definition is actions where the motivation of the perpetrator is the gratuitous pleasure in the suffering or death of others. One example might therefore be a serial killer. These are only song lyrics, but I think the Doors got it exactly right in Riders on the Storm:

“ There's a killer on the road. His brain is squirmin' like a toad. Take a long holiday. Let your children play. If you give this man a ride, sweet family will die. Killer on the road, yeah”

One might argue, of course, that such a person has severe psychological problems following childhood traumas. But is that really an excuse?

I agree with you that evil is not a real thing, at least in a non-dualistic context. It is, however, real enough at the human level, as you say.

Your other point is correct. We never accuse Nature of being evil, even though it appears red in tooth and claw. As Genesis 2 says, it is specifically a problem of being human.