What does understading evolution teach us ?
Darwinian Evolution teaches us that all living things come about by natural cause,
Darwinian Evolution proposes that all living things come from decent with modification from an original cell. The natural forces of natural selection, competition for limited resources, over population, variations within the population can explain the creation of new forms of organisms observed in the world today.
Neo Darwinian Evolution teaches us that the variations within the population necessary for Darwinian evolution come about by mutations. These mutations are the result of random accidental changes in the DNA or genetic material. This teaches us that life is the result of accidental changes.
Darwinian and Neo Darwinian Evolution teaches us that life is the result of accidental changes and natural causes exclusively. The teachings of Neo Darwinian Evolution may not be true or helpful to society.
It also means that we had ancestors of course...
Every organism evolved to become smarter to be able to survive better in their environment. Changes in genetics and maybe some mutations (but highly unlikely) over generations can influence a rise in dominant species. It basically means that organisms change over periods of time due to their traits.
For a detailed explanation, see David Drayer's answer or read at: