Propaganda!

Battleship Potemkin- It presents a dramatized version of the mutiny that occurred in 1905 when the crew of the Russian battleship Potemkin rebelled against their officers of the Tsarist regime.

The Wandering Jew- The Wandering Jew purported to be a documentary depicting the Jewish world, insinuating that the Jewish population consisted of avaricious barbarians putting on a front for civilized European society, remaining indifferent and unaffected by the war.

Triumph of the Will- a film commissioned by Hitler to chronicle the 1934 Nazi Party rally in Nuremberg

To make money $_$. Films are made by private film companies(mostly), and private firms are always profit-driven.

The making and showing of motion pictures became a source of profit almost as soon as the process was invented. Upon seeing how successful their new invention, and its product, was in their native France, the Lumières quickly set about touring the Continent to exhibit the first films privately to royalty and publicly to the masses.

A film's purpose is decided by whatever the director wants to have happen with his or her film.

Not much to consider here.

In recent years, however, films have been increasingly utilized, whether consciously or unconsciously, to influence mankind, thus rejecting the idea that the sole purpose of a film is to entertain.

In modern society, films are not only used to entertain, but also to educate, inform, and in some cases, indoctrinate society. Film makers are continually tapping into the influential film industry to change mankind, and a good example of it would be An Inconvenient Truth, a 2006 documentary film directed by Davis Guggenheim, addressing the sensitive issue of climate change. In this case, a film was made, supposedly to educate, but upon further examination, one realises that a film can do so much more than just educate or entertain.

Other than the purpose of entertainment, some films have moral education embedded in them.

Take Avatar for example, which exemplifies the message that we should find happiness in nature, and that earth and all its man-made things are impossible to find happiness in, as Sully says later in the film. There is also the message about how man should be in harmony with nature and highlights the destructive effects of deforestation/global warming(indirectly)There are thousands of other examples, but the point is that most movies have some sort of message or moral education.

Films are a source of heritage preservation.

Films are produced and stand as a collective memory of the past as witnessed by the moving image. These films allow us to illuminate our heritage with a power and immediacy that is unique only to film. Furthermore, filmmakers may also present a different angle from what is recorded in history textbooks. This is because by shooting a film, these people are able to portray a more personal touch and tell a different side of a story. As such, the heritage of a certain country or cultural heritage of a minority group is thus able to be preserved on film and the legacy passed down after many generations.