That's too simple, if not downright mistaken. In the first place, some great non-fiction books may not be about striving of this sort. Edward O. Wilson's Sociobiology is one such that I remember. Darwin's On the Origin of Species, or Michael Behe's Darwin's Black Box, aren't about striving, either, unless you count the struggle for existence. This doesn't detract from their importance. (I recognize that there was, and is, controversy over the ideas in all three of these texts. Nonetheless, they are, or were, all important.) Non-fiction books may, of course, have striving against all odds as a central feature. Many biographies are about striving. I recently finished John James Audubon, by Richard Rhodes. Audubon and his faithful wife struggled mightily against great odds nearly all their lives.In the second place, some of the fictional books I remember had little or no striving against great odds. A.A. Milne's Pooh books don't. Some important science fiction works don't seem to have had much striving against great odds, either. I don't remember much of that in Arthur C. Clarke's 2001, for example. The book was mostly about theme and setting, with plot secondary. Jan Karon's Mitford series emphasizes characters and setting, not plot.
There are fictional works which don't feature striving against great odds, but moral choices. Perhaps that is striving against great odds, striving againstyourself.The Bible is a great book, and it does have a lot of striving, against great odds, to redeem fallen humanity. It also has a great deal about moral choices, of course.
Given the choice, I would usually choose a book which features striving against great odds.
Sunday, in church, we were directed to sing the odd verses of a song. I suddenly wondered why verses 1, 3, and 5 were called "odd." So I looked it up.
They are called odd because odd numbers of objects cannot be matched in pairs. One object out of, say, seven, is odd. Six of the objects can be matched in pairs, but not the seventh one.Why are seemingly hopeless struggles called "against great odds?" Odds has to do with the difference between one side and the other. Not an equal match, in other words.