Earlier quoted context omitted.
> Just because physics doesn't have a notion of identity, doesn't mean there is no such thing. How is that not exactly what that means?
Identity, like beauty, fun, and spiciness, is[1] something that's built on physics, not requiring a fundamental property, just as asking how much spiciness an electron has is futile. [1] Well, presuming it actually does exist as something other than confusion, which I'm not currently arguing, though I'm sympathetic to the notion.
Fun is an extremely vague notion, I'm not sure what it means or if it even has a consistent set of synaptic patterns (or whatever), but I think that's probably because people don't use the term consistently (or are confused, etc., as you say).
Spiciness is absolutely purely chemical.