Obviously the ancient Israelites did not have apples, and from what I can tell, scholars are undecided as to what the authors of the OT would have been thinking of in Genesis. But at some point, people seem to have begun commonly referring to it as an apple. When was this? Why?
Apples come from Central Asia. Wild apples are found in Turkey. They were almost known at the time in the area. That corrects your first sentence but doesn't answer the question itself. I suggest you ask in /r/AcademicBiblical for another chance at the answer.