No-one is mentioning the elephant in the room here; now granted the image isn't the best, but the shape of the object, that we can see in the image released, is not that far short of being approximately square, to my way of looking at it.
If - IF - the 24m dimension is approximately correct, I would eyeball the rough dimensions of object as 24m x 20m.
Call it 80' x 60'.
I'm struggling to picture what bit of a 772, when reduced to wreckage, could be that size or anything close to it. It's the wrong shape and size for a bit of wing or fuselage or tail.
I wouldn't get over-excited by this until we know a lot more.