This is the sort of question where it is better for you to answer on your own. My opinions will not necessarily be the same as yours and so my answer cannot really take the place of your answer. What I will do in this answer is to lay out the main points of the Prologue. You can then look at those points and decide which ones you do or do not agree with.
In the Prologue, Diamond first sets out the question that he is trying to answer. This is Yali’s Question. Yali was a man from New Guinea that Diamond knew. Yali asked Diamond:
Why is it that you white people developed so much cargo and brought it to New Guinea, but we black people had little cargo of our own?
Diamond could not answer him at that time. Guns, Germs, and Steel is Diamond’s attempt to answer Yali’s Question. He broadens the question to ask why it is that some societies became rich and powerful while others did not.
Before starting his own argument, Diamond says that some people might think we shouldn’t answer the question. First, he says some people might think that answering the question will justify the way things are. In other words, answering it will make us think that it is morally good for Europeans to have come to dominate the world. Second, he says that answering the question might make us focus too much on Europe and the United States and make them seem more important than they are. Finally, he says that answering the question might imply that it is good to be “civilized,” rich, and powerful when it really is not so. Diamond says that these concerns are wrong and that it is okay to answer the question. Do you agree?
Next Diamond lays out some common answers that other people have given to explain why Europeans came to dominate. First, he says that some people say this happened because white people are simply better than non-whites. On pages 20-22, Diamond refutes this idea. He says, among other things, that New Guineans are probably smarter than Westerners because they do not spend as much time doing mindless things like watching TV and because being smart doesn’t really make you more likely to survive in civilization. Read these pages for more detail and decide if you agree.
Second, Diamond says some people think that people in bad climates came to dominate the world because they had to work harder. People living in tropical climates could have easy lives and so they did not have to work hard or invent many things in order to survive. On p. 22, Diamond says that this is not true. Do you agree with him?
Finally, Diamond says he believes that geographic luck is the answer to Yali’s Question. He believes that some societies became rich and powerful because they were simply lucky about where they were on Earth. Do you agree?