[ethbr0]

They may point to the middle, but that's not a reference to half an object. ;)

The assumption is that the thing is its entirety, as you said.

Hypothetically, I imagine an array index reference, in human terms, would be communicated as "this thing starts here" or "this is the beginning of this thing."

Which isn't a concept or phrasing we have much occasion to use, other than for routes or long length-measured objects?