@C8H10N402 erm everyone is giving an assumption or opinion..... many of us also live or have lived in rough areas where this would be an opportunity.
I think given the Ops summary that the neighbour is not the thief.....
My comment about normal driver is fair game, it may well be a seasonal driver, a seasonal driver is more likely to be an opportunist, it's not me being a snob it's just how it is, they are low paid, very likely to have children and it's Christmas.
As has been said multiple times, they don't usually wait for a door to be answered if your upstairs, it's very much a dump and run as their wages are crap so for the neighbour to say he was there unusually longer than normal strengthens the argument and so does leaving it in a completly random place.
I think it's a seasonal temp, he's moved the pot to make way for the parcel and spotted it.....dithered over it, took it but to make it look less suspicious has left the parcel nowhere near the porch as if he was never there hence the longer drop time.
Sadly we don't live in a fairy bubble where no-one ever does wrong things.....the world is full of opportunists, thiefs, liars.....given the summary of events it really doesn't take much processing to figure it out but with no solid proof it's never going to be a conviction but we will make assumptions because we are human.