Can we say the human race won The Great War in No Game No Life: Zero or Tet won?
The main aim of Riku was to end the Great War so that they can live in peace. So basically the win condition is achieved at the end of the movie. Thus we can say that the human race won the war because:


Peace achieved.
Human race recognized (as exceed) and given the name Imanity by Tet.


Bonus:

There is a very hot debate about how Riku died and it's not %100 clear. Some even say "Riku actually become Deus before dying and created Tet unconsciously". However, it's pretty obvious that Riku didn't plan anything related to Tet. That's is why there is no clear answer to the question "who".