I know why there is good and evil.

K.

What a good thing it is that the police don't take that view.

So... why is there natural evil?

Lol, couldn't find an answer on google, huh?

At first glance, this sentence did not look as nonsensical as most of your posts.
On second glance, however...

Humans have free will because of evolution.

First, evolution did not provide humanity with every choice imaginable.
Second, you don't need every imaginable choice in order to make a conscious decision for a choice. Two alternatives of equal worth are enough.

Evil and good are relative and subjective. Therefore "low" and "high" are problematic categories when it comes to moral values.

But I did say that at first glance, your post wasn't entirely nonsensical. If we reformulate some points, it becomes more sensible.

If you are going to bestow free will upon people -> If people can make conscious decisions
you have to provide them with every choice imaginable -> they have the ability to make choices
from the very lowest to the very highest -> which can be ethically desirable or undesirable

"If people can make conscious decisions, they have the ability to make choices which can be ethically desirable or undesirable."

Not too stupid in my opinion.