For me, the Greek Ollendorff, with its methodical and extremely simple progression, was a perfect vehicle for recording and then listening, as an autodidact's way of complementing grammar study with the development of some natural feeling for the language. I wouldn't recommend the Ollendorff as one's sole or first general introduction to (yes, Attic) Greek - there's too many excellent and much more contemporary resources for that.
As for a "gentle introduction toward reading Aristotle [in Greek]," there's no such thing. In addition to the complexity of its subject matter, the style of Aristotle's works is generally that of classroom notes, highly abbreviated and full of shortcuts. I'm no expert, but decades ago as a classics PhD student I took a graduate seminar on Aristotle that was focused on his compositional style, and I remember it took considerable effort to begin getting comfortable with it.
If your goal is to read Aristotle in Greek with some facility, I suggest you need several years of preparation, learning (Attic) Greek in any of the standard ways and then reading other more "connected" prose first (Xenophon, the "early" dialogs of Plato, some Thucydides, maybe some of the Attic orators, ...).