Granted that the wreck was on the sea floor for 2,000 years, my quite minority view remains unchanged, that the ship was carrying random salvage, a common thing during the Roman Empire just as it is now. The Mechanism itself may have gone out of date, or may have been intended for sale, but it just as easily could have been broken into pieces for recycling before it was loaded. I think the statues were also fragmentary, and mismatched at that.
It would be interesting to learn if this was one of those great big grain haulers, but ships ireespective of size carried lots of different cargo to spread the economic risk as they called on more than one port. According to the late Lionel Casson, the Roman grain haulers were so large that only a few places in the Mediterranean were able to handle them -- Alexandria and Rome being the main ones.
How large are we talking about for these grain haulers?