When did movies become art?

Motion pictures began in the 1880s, but they were novelties. It was not until the 20th century that they began to have a wide following.

When did the novelty end and serious endeavors begin, and when did it become art?

Is there a film or director that can be seen as giving birth to the art?

Here is an early film from 1902.

Here is D.W. Griffith’s The Country Doctor, an early attempt at adding plot.

Finally, in 1916, D.W. Griffith came out with Intolerance, a 3 hour silent film that broke all bounds.