I'll cut to the chase. I don't know a whole lot about the Halo story.
My Questions:
1) If the Forerunners created the Halos to wipe out all life so the Flood wouldn't have a source of food how do the humans exist?
2) Also, If the rings were activated why did we come across them? They'd have been destroyed.
3) Lastly, If the rings wipe out all life, how did the Flood survive?
3.5) I lied, this is my last question, Why/How were the Flood locked up on Halo in Halo: CE?
You guys are the Flood so you of all people should know about the Flood. Like I said I don't know much about the Halo plot so this could all be one giant mistake.