The First Age of Mankind
In the First Age of Mankind, mankind was created, not just man, not just human kind, but the younger races.
There was the First One, Lorien, and his people. They were masters of this galaxy, and they witnessed the birth and evolution of the First Ones. The Shadows came first, then rest of the First Ones, including Vorlons.
Mankind was insignificant, they were too primitive to be of any concern. These younger races were left to themselves, as the First Ones evolved their Space Faring civilizations.
In this age, the Jumpgates were built, who built them is still a mystery, but the younger races know that it was not the Vorlons, nor the Shadows.
The First Age of Mankind ended when Lorien's people left the Galaxy, beyond the Rim.
The Second Age of Mankind had begun.