<em>Inflexible</em> refers to something or someone that is not able or willing to change or adapt their opinions, habits, attitude or ideas, similar to a stubborn person who refuses to change their opinions, habits, attitude, ideas or positions, especially in spite of good arguments or reasons to do so.
In the passage, the sentence "He answered with inflexible humility" conveys that he answered with a determined or stubborn humility, meaning that he had no intention to act without humility.
The quote means that to be a part of your community, you have to be like everyone else. If you are not like everyone else than the other people in the community will just ignore you or treat you as an outsider.
The Cornell method has been proven to be very useful & is used throughout high school/college education. color coding notes & making them aesthetically pleasing can impact your focus on the info. flash cards or repetition is helpful in the memory process