What the author “meant” is vastly overrated. The author is dead is sometimes more literal than other times.

We can pull information out of the text on its own. We can get cultural context to see how they would approach it. In OP’s case of the apple, we know that the term “apple” was a generic term for fruit for much of English history (and still is in some other European languages). We also know that what we call apple trees now don’t grow in that region, and therefore, it’s almost certainly not that kind of apple.