Is nature inherently cruel and does natural selection depend on this cruelty?

By cruel I mean non-discriminatory and random. A cat will dangle a mouse between its paws for curiosity or fun, apparently unaffected by the distress it is causing it. A flood can come and destroy all the edible crops in a region, leaving all the animals who rely on it to starve, and in turn giving its competitors a chance to survive and thrive. It just seems extremely random and cruel that some species survive while others die out.