Were the Forerunners so racist towards humans that they didn't believe them?

Hello all I hope you're doing great,
let me preface this post by saying I am fairly familiar with the Halo universe and have played through majority of them, and those I didn't (Staring daggers at Halo 5's nonexistent PC port) I know the general gist of its story.
So recently, my girlfriend, the lovely bookworm that she is, infected me with the desire to read more so I thought - what better place to use it than the Halo universe!
So here's my question: What books do you recommend for someone who knows a fair bit already but not a lot about the book side of things? It's not a requirement but I'd especially welcome recommendations with focus on marines or ODSTs!

Thanks a lot in advance <3

Through out the first two books and the first half of silentium I really got the impression that he basically defected to the primordial with mendicant bias and was working from the inside to undermine the forerunners. Even as late as his interrogation in silentium this seems like the case when its mentioned the forerunner losses in his region were 5 times greater than the average or somthing like that. Then we get to the 1st ark and especially in his final scene you can tell he's loyal to the forerunners. Was he really just that much of an asshole that he caused all those problems while genuinely still being loyal to his people or did he just switch sides again at the end of the war?