Neither Watt's steam engine nor Whitney's standardized parts really started the Industrial Revolution, although each has been awarded that claim, in the past. The real start was the awakening of scientific and technological thoughts during the Renaissance, with the idea that the lawful behavior of nature can be understood, analyzed, and manipulated to accomplish useful ends. That idea itself, alone, was not enough, however, for not until the creation and evolution of blueprints was it possible to express exactly how power and parts were to be combined for each specific task at hand.
Douglas T. Ross, "Structured analysis (SA): A language for communicating ideas" in: IEEE Transactions on Software Engineering Vol. 3, No. 1, Jan 1977. pp. 16-34; p. 16.