No, he didn't invent the cliffhanger or the close-up. But more than any other director, he knew what to do with both, and is still identified as their originator to this day. Nobody made such a fine art of rescuing beauty in distress, to the thunder of hooves (imaginary, of course, in the silent movies) or saving the condemned man from the rope as the messenger gallops up, waving the reprieve.
The beauty in question was usually Lillian Gish, a deceptively fragile and delicate-looking figure who was in fact a powerful, articulate actress, well able to take care of herself. She referred to him as 'Mr. Griffith' to the end of her long life - a mark of the deep respect in which the industry held him. In the anti-climactic second half of his career, this hero-worship may even have got in the way. Someone commented "He was too big for the industry. He was looked upon with too much awe." He was also liable to overspend as though there was no tomorrow - which eventually there wasn't.
Today he is at the centre of the race controversy, due to 'Birth of a Nation' - by far the greatest film of its day, by some standards the greatest ever, but blamed for re-awakening the Ku Klux Klan, and long since banned from a thousand screens. Griffith was a Kentuckian, who grew up listening to a highly dubious version of the civil war from his ex-confederate father. Kentucky, of course, was a slave state that had stayed loyal to the Union, and was also Lincoln's birthplace. This could explain the strange slip when the narrator refers to Lincoln as 'a hero of the south', which he never was. It may also explain why Griffith chose to make a bio-pic of Lincoln, when the studios no longer had big projects to offer him, but were still prepared to make use of his detailed historical knowledge.
One puzzle remains. The earliest clip ever filmed in Hollywood (1910) shows an open car driving to the top of a hill and two men getting out to overview this new location with its brilliant sunlight. They were Griffith and Mack Sennett, two of the most acclaimed directors on earth, arriving unexpectedly in the domain of the cheapest and shabbiest film-makers, who were using Edison's patents without a licence, and might need to hop across the nearby Mexican border. Is it true that these two were being sought by police over the under-age mischief of which the film industry was strongly suspected by the city fathers of New York?