Answer and Explanation:
One of the most easily recognized themes in "Of Plymouth Plantation" is the aversion that Bradford presents when talking about Native Americans. In chapter 4 of book 1, we can see that Bradford uses logos to claim that Native Americans are not human beings. This can be seen through the lines "Those vast and unpeopled countries of America ... [were] ... devoid of all civilized inhabitants and given over to savages ... differing little from the wild beasts themselves," where Bradford reinforces that if America is unpopulated, it is logical to say that its inhabitants are not human, but something close to animals, without civilization and lost in the wild. This shows the European position in relation to indigenous tribes, which provides us with a preview of the European attempt to subdue and dominate the natives.
Another easily identifiable theme is the certainty that the difficulties will be overcome. Still in chapter 4 of the first book, we can see that Bradford says "All great and honorable actions are accompanied with great difficulties, and must be both met and overcome with answerable courage," which shows that he observed all the challenges that the colonists faced in America they would be rewarded if they faced them with courage. That's because for Bradford, they were doing something honorable, very big and very complicated, but that would train and test their merit to be rewarded.