Genesis opened the door. It did not build the whole house.
St. Dorsey is the launchpad for the modern public superhuman age, but OldRoot is larger than one incident. Genesis was an accidental Abyron catastrophe that changed a small, finite number of survivors into Ascendants. Their exact total is not treated as public in-universe knowledge.
Other heroes, villains, anomalies, technologies, experiments, artifacts, magic systems, aliens, and future forces can come from entirely different origins.