Because you do so much non-signaled “jumping around” from head to head, because your dialogue mechanics don’t function well, because you don’t have a well-enough-focused main character, because you over-describe settings and places, because of the arcane technical nature of many passages, because, again, one scientist’s findings alone wouldn’t be enough to compel world attention, because too much time’s occupied with the creation-evolution debate, etc., your narrative doesn’t run smoothly and quickly as it should (and this kind of novel should make reading 500-600 pages seem like just 150 or so are passing).
As you now have things, far too many minor characters try to make up for lack of a compelling major one, and too much extraneous material keeps this work from having the sort of plot skeleton it needs to be solid fiction. And it may be necessary, if you feel you lack the skills to reconceive the story with Y as your major figure/antagonist, for you to consider dropping a novel-narrative framework altogether and to think instead of presenting the ideas you’re concerned with in a series of loosely connected essays. Novels of ideas only work well if they’re also good, soundly crafted fiction.
I’m not sure, frankly, that you have the storyteller’s instincts and gifts to craft such narrative. Yet you do share, as I wrote earlier, numerous intrinsically intriguing ideas. Why not write them to stand on their own? Right now, in narrative form I feel they kind of trip all over one another, so even as ideas they end up not being expressed as well as they might be if you drop the storytelling trappings.
I’m not sure to whom this book would appeal in its present form. At the moment it’s too much of a hodgepodge to work as a novel; you’d have to reformulate it considerably to make it into a working novel; and you couldn’t merely isolate parts of it to make effective essays. Wish I could be more encouraging; I hope you’ll appreciate my giving it you as straight as I can. I can’t advise just which direction novel or essay collection you should take at this point; much of that decision will depend on your inclination to work on either fiction or exposition. I hope you’ll do some hard thinking about the course you might take.