In the human genome it is estimated that there are more than 30,000 genes. In sexual reproduction there is a vast number of possible combinations and expression of these genes.
Natural selection can not produce information it can only choose the information best suited or adapted to a particular environment by eliminating and causing the extinction of those variations that are less well adapted.
Sexual reproduction provides a vast selection of variations for Natural Selection to chose from. Think about all the variations of humans on the planet some suited to some environments better than other variations.
The genome of the grey wolf has given birth to a vast array of dog breeds. Artifical selection has chosen different variations of the genome, eliminating some parts to create. all the different varieties of dogs, that are still the same species.