re: Question about end of Interstellar: Dr Brandt (SPOILERS)

Without the black hole and time travel aspect plan A would have failed. Humanity that was on earth would have died out. The plan B colony would have been the only surviving humanity. They would have simply evolved as the only remaining humanity to higher beings who could manipulate time. This is assuming that the beings who helped with the wormholes and time portal in the black hole are in fact humanity's descendants.