As it was relayed, the apple thing was the moment that he realised that the mysterious force holding the celestial objects in their orbits was exactly the same

As it was relayed, the apple thing was the moment that he realised that the mysterious force holding the celestial objects in their orbits was exactly the same force as gravity. It's not that gravity was a new concept or anything. In fact, it goes back so far in our history that we still use the silly name "gravity" for the phenomenon; it was once though to be a property of an object or an element (in the "four elements" sense), and was opposed by another property called "levity". You will note that there is no current theory of levity. Galileo had already put numbers to gravity on Earth by that point, and the idea that the force holding things in their orbits acted according to an inverse square law was circulating before Newton got there. (There's no reason to believe he couldn't have come to that conclusion independently, but there's no reason to credit it to him either.) What was missing was the connection; the generalization. That's not obvious in any way. How do you get an inverse square law to work with Galilean gravity? It smacks of equants and deferents until you find a way to put the effective mass of a body, such as the Earth, at its centre. Imagine a world in which there's some inverse square force thingy holding the moon and planets in their orbits, and there's gravity and you know how that works, and nobody has even the slightest notion that they're in any way related. And then you have the OFFS moment.