I probably read this book like 6 years ago. I know for sure it was part of a series because there was a lot of back story I missed out. It takes place in the future and humanity has for the most part been wiped out. What remains are a few mutants on renegade planet and the genetic makeup of a few humans that is used to make clones. I think they were able to keep this one chick's brain/spirit/mind in a computer or something for a while but that eventually went away or became full-on electronic.
Anyways these clones, or whatever, form an alliance with these giant grasshopper people. And then one day boom this gargantuan solar system sized ship comes their way. I guess the grasshopper people knew about this galactic killer so they were kind of ready and they decided to help the humans. Anyways they all try to hide out in their respective mother ships and they're like tiny cells entering into this massive organism. Well inside the ship they discover there are wars going on in a massive scale. Different species trying to fight it out for survival in space ships fighters, and massive cruisers.
Anyways I don't remember how the book ends. I think they all made it out in the end but they had to find a certain part of this ship or something. I remember the way the author describes the battle was like if you took our white blood cells fighting an infection. He/she tried to make it sound like the giant ship was an organism and by destroying systems it was really just trying to live… No it wasn't Galactus.
Anyways sorry if I'm too vague but this is all I can remember.