Moses is not mentioned in the Hagaddah (with one minor exception), presumably to show that the exodus happened entirely by G-d's power and to not deify Moses.
Presumably, though, the maggid during the original second seder (a year after the Exodus) mentioned Moses since they knew him and since most stories involve human actors (e.g., Shemot through Beshalach).
I understand there was no fixed Hagaddah until the Middle Ages, but I assume the text evolved over time, and that the traditions of the Hagaddah are older than the text.
So the question comes down to - how old is the tradition to exclude Moses from the Passover maggid? Does it date back to the Talmudic era? King David's time? The midbar?