The best answer is that they carved huge monumental heads which may represent their kings.
This is one characteristic unique to the Olmec people. They build stone heads of colossal size that were nearly 3 meters high and 8 ton in weight.
The stones were carved in Basalt and all of them display unique facial features such that they can be considered to be portraits of their rulers
The stone from which they were carved was in some cases transported 80 km from source to the capital.
Olmec culture also included ball games and drinking of chocolate . These practices were passed on to other civilization that later arose.
