In fiction, are the reactions of readers to the people and events of the story are more important than the people and events themselves?
I think a case could be made for both sides of the question. Without a story (the people and events about which one reads) there can be no reaction by readers. To that extent, then, the answer is false. But, because an author wants to create characters and events which will be compelling and cause readers to react, the answer is true. Probably in the middle somewhere is the truth.
Outside the culture of "pop" fiction, which is all about readership and book (or e-book) sales, writers generally write because they have something to say, whether anyone ever reads their work or not. Wanting their readers to hear them and then react or respond is second to expressing themselves in writing. Interviews with and reflections by authors in all centuries seem clear about that fact. Just as the sun shines whether we appreciate it or not, so writers write whether anyone will read and appreciate their work or not. The same case could be made for musicians and painters. Even without an audience, most of them would still create.
On a practical note, though, authors also want to share their themes and perspectives and styles with others; it's just not always their primary motivation.