You ask a good question. What is the source of evil? The famed Jewish sage, Moses Maimonides was of the opinion that G-d does not cause evil. G-d only does good. Thus, evil is the result of one of three things. Three events cause harm. People harm themselves, harm others, and natural law, which is good for the world as a whole but may harm individuals. For example, a hurricane cleans the earth but may kill people. However, nature is not really evil. Humans perceive it as such because they are too self-centered. In contrast to human suffering, the Rambam writes that most suffering is self-inflicting.
When Isaiah described lions lying with sheep and beating swords into plowshares, these were parables (Maimonides). The Rambam writes that he was speaking figuratively about an ideal society. Interestingly, but to the surprise of many, Rambam did not think the laws of nature will change in the messianic age. Rather, Jews will have political freedom.
Also contrary to the beliefs of many, Maimonides felt that G-d neither needs nor wants sacrifices, but "allowed" Jews to have them as a concession, a concession to the primitive nature of human beings. Maimonides wrote that there seems to be a law of nature of the principle of gradual development. Things develop gradually. Just as flowers sprouts in stages or steps and not by leaps, so too do the people of Israel, spiritually.
From this view, we see that Maimonides showed much compassion for animals. He correctly understood that animals, like humans, have emotions and can feel pain. For example, Maimonides says that the commands of Deuteronomy 22:6 and Leviticus 22:28 recognize that animals have feelings.
Similarly, the Seven Laws of Noah prohibits eating flesh from a live animal. People should respect animals, for they also have feelings. We should even be cautious when walking as not to trend on ants. This is why a person does not take the eggs from a bird’s nest if the mother bird is near, for the mother can not bear to see her chicks taken before her. This is why people should chase the bird away. It may even prompt the person to feel sorry for the chicks and leave the eggs alone. We see from here that it is prohibited for people to torment animals.
It is worth noting here that originally humans were vegetarians (Genesis 2:16). It's only after Noah's flood when the Torah gives permission to eat meat (Genesis 9:3). It seems that the Torah prefers a vegetarian meal, but recognizing human desires, allowed people to be carnivorous.
I will end this discussion with G-d and natural laws.
Nachmanides believed in "hidden miracles," like the falling leaf. The great sage felt that no leaf fell from a tree unless G-d decreed: “fall, keep falling, keep falling, keep falling, stop, now lay still.”
Maimonides disagreed. He felt that it is not ”through the interference of divine providence that a certain leaf falls [from a tree], nor do I hold that when a certain spider catches a certain fly, that this is the direct result of a special decree and will of G-d due that moment… In all these cases the action is, according to my opinion, entirely due to chance, as taught by Aristotle…"
It seems as though Nachmainides did not believe there were laws of nature. Maimonides, in contrast, believed that there were laws of nature that govern the universe. Leaves falling, in general, is G-d's plan (we might call this gravity). I accept the latter view because it fits well with science. Since G-d is perfect, this must be the best of all possible worlds. Since G-d is perfect, everything is "good" and could not be other than what it is. Indeed, the Bible says that G-d created the world "Very good." It implies that G-d is not like a plumber, who needs to return on a daily bases to modify His creations because it is in a state of flux.
When Job hears G-d’s voice, after his suffering, G-d explains that his friends, who attempted to explain his suffering, are unaware of how the world operates. The world works according to natural law and will not change no matter how passionately one prays for G-d to alter nature. They fail to understand this because they are too selfish. They think the world was created for them; that they are the center of the universe. They think that the world operates according to a moral basis of principles of good and bad. They mistakenly think that when tragedy befalls them G-d responds like a loving father with care and warmth consideration. That G-d oversees human behavior and judges accordingly.
No, says G-d. The world is like a whirlwind. The earth is full of violence. The lion pounces upon the deer, tears it apart, consumes it. Humans, naturally being naive, wish to see the world through a lens that fits with their understandings of morality. They fail to recognize the reality as it really is, that the world functions as G-d wants it. People need to accept the world for what it is, and not want they want it to be.
 See Mishneh Torah, Law of Kings, chapters 11 and 12
 On gradual development, see Micah Goodman’s “Maimonides” for further discussion
 Guide, 3:48. Translation of M. Friedlander, 371.