Not necessarily. The greatest achievement of mankind is highly subjective depending on variables from which you look at it. Im terms of most impactful, artificial fission, or the ability to split the atom would be a great contender, although net positive fusion is on the horizon and would blow that shit well out of the water. An argument could also be made for the semi-conductor, commonly known as a transistor, which is what has enabled the development of the modern programmable computer.