Your rose smells nice because it was bred to smell nice by human breeders. All the different varieties of cultivated roses that we have today are the product of hybridizing and selective breeding (“artificial selection”) of twelve or so wild rose species; a process that has continued over hundreds if not thousands of years.

While not a hard and fast rule, most plant species with strongly scented flowers usually are white (jasmine, gardenia, etc.) and pollinated by nocturnal animals like moths and bats. (A great counter-example is corpse flowers, which use scent to attract a completely different guild of pollinators).