Natural Selection, was made famous by Darwin in the 1800’s. It works by having a population that is changed because natural circumstances favors the survival of one organism over another. The favored organisms flourish, others go by the wayside.
A famous example of Natural Selection is moth coloration in industrializing England. Before pollution darkened the trees and killed the lichens, you had a population of white moths. As the trees darkened, white moths were easy prey for birds, and the population shifted in favor of dark moths. When the pollution went away after WWII, they became white again.
Eureka. A new type of life… but were they really. On close examination, we see that both colors were already in the gene pool. New pigmentation genes did not just form. Now what if the factories were making blue dyes in the city and it coated the trees. Would the moths turn blue as well? No. People often confuse selecting from an existing gene pool with the creation of new life forms.