"Gray will play Dr. Miranda Keyes, a brilliant UNSC Commander who is dedicated to understanding the technology, language and culture of the Covenant, but she’ll have to learn to navigate the politics of the UNSC to get what she wants."
"an orphaned human who was raised by the alien Covenant and shares their contempt for humanity"
Doesn't seem like the UNSC and Covenant are involved in a total war of annihilation from those two quotes.
In addition, it's harder to create a show involving around a hot war. You pretty much lose all the political intrigue as your side is fully unified against the other. Less interactions and less conflicts because everything devolves to being about the bigger conflict.