The underlying theme of Marvel and DC comics character based movie is 'good guys prevail over bad ones'. It is simple, after all the inspiration is from the world of comics meant for growing kids entering adolescence. Occasionally this fight or conflict is used to make a commentary about the way we live our lives. Being imaginary characters, the tradition of comics is to generally opt for 'beyond nation states or other prosaic identifications' so that it provides the fulcrum to make a meta-point about humanity. For any such meta-commentary to succeed, it is critical to transport the audience effortlessly to 'a station' where what characters are saying is heard in all earnest. That is the trick director Patty Jenkins has been able to pull off in this wonderful movie.
Nowhere there is any pretension by Jenkins that this film is nothing but a make-believe story telling. It is all imaginary. But by crashing that 'fiction' in the hard and grim reality of World War I, by unravelling the 'innocence' of Wonder Woman slowly over the span of the movie; Jenkins created the space or context to ask the primordial question of humanity - why do humans become so reckless to kill off each other to an extent where extinction of humans from this planet becomes a real possibility? The director presents Diana's love for Steve as a proof that 'love' is a convincing answer for ills of humans and our proclivity to destruct one another.
The sequencing of major scenes, coherent unfolding of the plot, competent cinematography and reasonably good performances by Gal Gadot and Chris Pine; all achieve the purpose of taking the audience in a 'reflective mood' where the questions of 'war and peace' can be debated in a mature way. Too often in our today's politics, we are routinely turning our back to the reality and facts and refusing to ask and answer some obvious questions. It is only Diana's slow comprehension of how human mind interacts with other people makes it possible for us to ask these fundamental questions and prepares us to be receptive to answers which are so openly revealing in front of us. The director and scriptwriter were smart to demonstrate that in the end, it is few 'humans' who saved Humanity from the disastrous chemical weapons. Diana was the inspiration. She does only two fight scenes of significance - one to liberate a village when she answers the question of "when to help needy" by effectively saying "now" in an emphatic and spectacular manner.* The other one is when she makes her stubborn statement against the "hopelessness of the humanity" as cunning Iros has been waiting for ages for mankind to annihilate itself. While Diana wages these other worldly battles for morality of humans, in the concrete "here and now" world of humans; it is only the goodness residing among ordinary people who undertake heroics to bring us back from the precipice. The movie renders two parallel worlds - the grim and real world of "here and now" inhabited by Steve and his ordinary friends; and the ideal world of "where Humans ought to go", inhabited by Diana and Amazonian People. The beauty of the movie is by making violent and bewildering clashes between these two worlds, with full utilization of artistic freedom, the director has opened the audience for a larger debate; a classic use case of 'pure art' is fully attained by this movie.
* But alas, ultimately her saving of villagers does not work; they all die in the test chemical attacks.