What's interesting (to me, anyway) is that most of the things I've read and seen have different views of what's going on, just as I predicted. Here are the more interesting interpretations I found:
From Film Reference:
The Little Island, which took three years to make (and is said to be the longest film ever drawn and animated single-handedly), is a half-hour philosophical allegory; Roger Manvell called it "at once absurd and violent, madly serious and wildly funny." Three small, pear-shaped people land on a desert island. They personify, respectively, Goodness, Beauty, and Truth. Goodness and Beauty, dangerous monomaniacs, soon clash, piling increasingly grandiose structures on their rival concepts, until they metamorphose into ferocious monsters whose vast collision shudders the globe. Truth, meanwhile, bemused and conscientious, keeps score on a blackboard which takes on the shape of a nuclear bomb. The film uses no words; the most complex abstract ideas are brilliantly conveyed in purely visual terms.
Screenonline said of it:
a philosophical treatise playing out the obsessional imperatives of 'beauty', 'truth' and 'goodness' as competing monsters, indicated his interest in the compulsive side of the human spirit.
The book Cartoon Modern, previewed via Google Books, calls The Little Island
a dialogueless modern morality play-- "three figures representing Truth, Good, Beauty, done in cartoon terms, all marooned on the same symbolic island," according to Williams. In their attempts to convert each other to their idea of the absolute "right way," they ultimately end up destroying one another.
Another book, Masters of Animation, sums the film up succinctly:
Beauty, Truth, and Goodness, represented by horrid little monsters, pursue their obsessions to an inevitably disastrous conclusion.
Using Babelfish, I got this translation of a French blog:
Three small catches unload on an island. One incarnates the truth; the second, the beauty; the third, kindness. Very quickly, each one of them will try to impose its delirious monomaniaque with the others. This strange postulate is the starting point of thirty minutes a dumb cartoon film, going back to 1958....A pretty pre-psychédélique hallucination whose absurd humour announces Shadoks.
After reading those views, consider what Richard Williams himself has to say about The Little Island. From a Clapperboard documentary:
It was a half hour allegory...it was a satire on people who have fixed ideas. And I found, or thought at the time, that people either believed in Truth, and they were all very Eastern or into studying science or "we will find the answer to this!" and their lives were focused that way. Or they would be like I was, some sort of producing artist with a great aesthetic point of view, and who would believe in Beauty or something. Say like Hemmingway, somebody who judges his entire life by his artistic output. And then the social man, who'd be the great reformer or a person who spends his life being friends with everybody or terribly involved, socially. So that, I found that the film was about the man who believed in Truth, the man who believed in Goodness, and the man who believed in Beauty, and that...was their fixed conception, and never did the twain meet until they all collided and turned into a sort of terrible, monstrous battle in the end.
And there you have it.
(File this one under "looking things up on Google so you don't have to.")