Well, where does one begin?
Tiwanaku
Yes, the buildings there feature some truly monumental stones. The largest apparently is just over 130 tonnes. And many are about 40 tonnes.
In comparison, Stonehenge standing stones weigh a mere 25 tonnes. Yet some of the Stonehenge stones came from a hundred miles away. While the Tiwanaku came from much nearer - a mere (!) 10 km.
I'd say it's a phenomenal achievement for a pre-industrial civilization. But, still, it's not impossible for them to have done so. Evidently. I don't think it indicates that the Andes must have suddenly shot into the sky 15,000 years ago.
Where is the evidence that it was a sea port?