It's not a terribly developed book. The characters are fairly flat and static, and the plot is simple. It may share a profound idea, but so does Dr. Seuss. The language is stark and at times beautiful, but it is not complex.
The animal imagery is potent in The Pearl, creating the concept of predator and prey, weak and strong, which is so much a part of life. Perhaps, Steinbeck's disillusionment with World War II and its theater of prey and predator played a part in his making of the novella which symbolizes the exploitation of the Europeans in the Americas.
One interesting aspect about the novel is that Steinbeck originally intended the story to be made into a film, which is why it is written in such a visual style. The simplicity of language and the visual appeal is another plus in its favour, in my opinion. It is something that everyone can understand and visualise.
I assume you are talking about the entire novel and not simple the pearl itself. The novella is a cautionary allegory about the importance of working together against an evil force instead of trying to overcome that force individually. It expresses a common dream of many people, to suddenly find something that will you rich, be it a pearl, lottery ticket, inheritance or gift from a millionaire. It explores this wish and human greed in the form of a story about a young Mexican peasant who finds "the pearl of the world." The only problem is that he must first be able to sell the pearl for its real value and not be swindled by the pearl buyers and the Spanish power structure. As such, it is a valuable literary tale that is extremely accessible to all readers and contains a message and themes that many can relate to. Because of its simplicity, it is often overlooked but one close examination, it touches on a universal theme about the power of money and the need to work together to defeat an evil power structure.