It merely implies that Christians tended to take assertions in the Bible literally by default, when they knew of no good reason to think otherwise. That has been the attitude Christians have had throughout most of history, and it is not particularly irrational. Certainly it is radically different from the willfully irrationalist attitude of modern fundamentalists, who insist that everything in the Bible is literally true despite all evidence and argument to the contrary. It is this sort of willful irrationalism about teh Bible that is a very modern phenomenon, and I believe it is pretty clearly motivated by a fear and hatred of the social changes brought about by modern science and industrialism. Fundamentalists are not motivated by a love of the Bible. For them the Bible is a tool in their attempts to role back the social changes that they blame (perhaps rightly) on science.
Augustine was pointing out to some of his less learned Christian contemporaries that there quite frequently were good reasons to think otherwise than what might be implied by a simple-minded literalist reading of the Bible, and that Christians would be wise to take these seriously, and modify their understanding of the Bible as appropriate. His arguments were, to put it mildly, very influential, on both the Christians of his own time and of succeeding centuries.
Before the 17th century, however, there were no good reasons to doubt that the Earth was the center of the universe (not that the Bible says much of anything about this issue anyway). There were no good reasons to doubt it before the combined efforts of Copernicus, Tycho Brahe, Galileo and Kepler had made a case for heliocentrism (and no truly compelling reason to accept heliocentrism before Newton). Therefore almost nobody, Christian or otherwise, doubted that the universe was geocentric.
Likewise, in Archbishop Ussher’s time, there was no well understood evidence and no good arguments to suggest that the Earth was any older than the Bible seemed to imply it was. Indeed, in Ussher’s time the Bible seemed to be pretty much the only available source of evidence about the history of the Earth and the universe as a whole. Geologists had not yet learned how to read the stratigraphic and fossil record. Once they did, Biblically based cosmology went out of fashion quite rapidly, despite the fact that nearly all of the geologists involved were sincere Christians (or, at a minimum, in some cases believed in a Deistic creator God).
Pretty much everything in the Book of Genesis, for one thing. He wrote a whole book (maybe more than one) about how Genesis could be interpreted in terms of multiple levels of metaphor and allegory.
I do not think even fundamentalists think the parables of Jesus are true stories. Indeed to do so would fly in the face of what the Bible actually says.