Afterlife Crisis

For readers of Douglas Adams, Terry Pratchett, and P.G. Wodehouse, and fans of The Good Place - a tongue in cheek fantasy that imagines Isaac Newton in the afterlife.
Where do you go after you die? Detroit.
"Finally, a hitchhiker's guide to the hereafter." - Corey Redekop, author of Husk
Something's rotten in the afterlife. At least that's how it seems to Rhinnick Feynman, the one man who perceives that someone in the afterlife is tugging at history's threads and retroactively unraveling the past. Doing his best to navigate a netherworld in which history won't stop changing for the worse, Rhinnick sets off on a quest to put things right.
This would be a good deal easier if Rhinnick didn't believe he was a character in a novel and that the Author was changing the past through editorial revision. And it'd be better if Rhinnick didn't find himself facing off against Isaac Newton, Jack the Ripper, Ancient Egyptians, a pack of...