From the other translations race stands for that (a car race) or arms race, but I've yet to actually beign chapter 2 so who knows. Still, a race makes more sense than it being about human races.
There was someone in Thread 2 I think who said the Japanese text is roughly translates to "Species".
Yes, it's revenge. They use the word hundreds of times and it's a motivating factor for virtually every character. You may like how it came through in the final game, but come on, Kojima repeats his themes in like every other sentence of these games.
Gene --> Meme --> Scene --> Sense/Will --> Peace --> Revenge
Chapter 1 is about Revenge. And yeah I didn't like how it came through. Like I said in my post it makes Kaz a worse character and the other characters who are out for revenge are out for it for the dumbest reasons. Also the ending doesn't reinforce this theme at all. All the other themes you listed are reinforced throughout the games and are incorporated into their endings. When big boss tells me I'm big boss how is that about revenge? This game IMO tries to tackle too many themes at once and suffers from it.