Most Christians, atheists, and even the worshippers of Mammon (the largest of all Western religions) are agreed that the purpose of the Universe was to create Man. Some even more extreme sects hold that the purpose was to create Americans. (Last century, the dominant sect held that the Universe was created for Englishmen.) These beliefs are erroneous.
In the first place, it turns out that by far the most successful life forms, by any measure even including gross tonnage of living protoplasm, are bacteria. Remarkably few of these make their living as agents of diseases. Natural selection has selected them as surely as it has selected us. "Survival of the Fittest" is a bombastic catch-phrase that Darwin was far too meticulous to have invented. His term, most carefully chosen, was "Natural Selection". Now the reason that humans came to dominate almost all other vertebrates is not, as those who coined the name Homo sapiens fancied, intelligence. It is social organization and intra-group benevolence. It may also be hunting and inter-group ferocity, but anthropologists disagree about this. Anyway, among our nearest surviving relatives, those who possess very high intelligence and rather loose social organization (the great apes) may well become casualties of the extinction process any decade unless we actively protect them. Baboons by contrast, with far smaller brains but far stronger societies, can still succeed well enough to be regarded by their human neighbors as pests. The most interesting effect that intelligence has in this context is that it reduces the effectiveness of tyranny as a means of ruling a group. (Most, if not all, conflicts between otherwise well-matched human war machines in recent centuries have been won by the less doctrinaire party.)
If the characteristic evolutionary advantage of humanity is society, then natural selection requires us to care for the weak and unfortunate. Note that this is required specifically of humans and of some other animals, but that it does not govern totally self-reliant beasts, like leopards and grizzly bears. In those species, even infants are defended only by their own mothers, against all comers, including and even especially the males that will sire the next brood.
It follows that that there is no truth in the notion that nature requires humans to be callous. And that the idea of a self-sufficient or self-made man is poppycock.
Now let me address the question of whether Darwin's explanation of nature is cruel. The problem is not that the mechanism of natural selection is cruel. The problem is that the cruelty is an observable fact, even when human complicity is absent. Carnivory by definition implies the killing of one creature by another. All of us who eat meat, or even, as Albert Schweitzer pointed out, who keep carnivorous pets, are involved in the deliberate killing of other animals. Now unless we take literally Isaiah's vision of vegetarian lions, and if there is an Almighty Creator, we must conclude that the Creator is also in favor of such killing. There are a number of possible explanations/apologetics for this. To my mind, the least offensive is the proposition that God is not an arbitrary trickster, and decreed laws such that elementary hydrogen could be turned into something as interesting as living creatures by the processes at the heart of the stars, followed by the process of natural selection on one or perhaps thousands of planets, and that it was good in His sight.
The alternative, and the moral problem at the heart of the Creationist version of the story is this: it implies a God that deliberately and individually chose to create not only those animal modes of predatory behavior that strike us as cruel, but also every horrible disease known on Earth that afflicts humans or beasts. It is very difficult to reconcile the creation of rabies with a merciful God. A literal interpretation of the Flood story carries it even further - God had to have arranged with Noah that all the diseases would be carried along with him. Thus at least one of those animals must have been rabid. Unless, of course, God had originally created an even wider range of diseases, and in His "mercy" allowed some of them to be utterly drowned. None of this sounds like the God who scolded Jonah for caring more for a gourd plant than for the whole city of Nineveh. It sounds a great deal more like the Evil One.
In short, "fundamentalist" alternatives to the theory of evolution are not only deplorably bad science and provably false, they are ethically obnoxious in the behavior that they by implication ascribe to God. We really can't get out of the pain of knowing about the savagery of animal predators and the horrors of parasitism by blaming it on Darwin.