The Smritis or the Laws came first.
Parshara Smriti states that at the beginning of a new Kalpa Manu simply recalls the laws.
Na kashchitvedakartA cha vedam smritvA chaturmukham |
dharmAn smarati manuh kalpAntareantare ||
The author of the Veda there is none ; (he) the fourfaced (God), at
each succeeding revolution of a Kalpa, recalls to mind the Veda ; and
so does Manu remember the law (at each succeeding revolution of a
ParAshara Smriti 1.21
It does not say that Manu creates .. he simply recalls the already existing laws.
But human beings were created much later, by the descendants of Manu, as the following verse confirms:
Manu Smriti 1.61. Six other high-minded, very powerful Manus, who
belong to the race of this Manu, the descendant of the Self-existent
(Svayambhu), and who have severally produced created beings,