I thought the Humans used Terran? This may not be contrary to the rules of the game, should they be swamp or was it a glitch? All of these strange (to me) events may be tied to the first contact being made via a wormhole.
Humans can easily colonize swamp planets, I forget if they even need a tech first but if they do it's pretty early in the tech tree for them.
I meant HW, but I was probably wrong. When it said I made contact, it showed a planet far away that was Sol. I probably read that wrong and by the time I posted it hours later I crossed some wires.