So, in my defense, it's not that easy to tell that this is the first book in a series and ALSO in my defense, a book should end at the end, not just stop. This wasn't even a cliffhanger, this was just where Kaplan seemed to run out of paper.
I will forgive a lot for really interesting worldbuilding - which this has - but not at least wrapping up some basic plot points in a book that's over 500 pages? Come on. 
I will also concede that I have high expectations for Jewish books that clear the bar of "not being about either the golem or the holocaust" which you would think should be easy.
Although I am appreciating the current trend of sheydim + historical tragedy (pogroms, the inquisition, etc) and see what emerges. Granted, Jewish history is relatively low on "and then things were GREAT" so, like, some of this is inevitable.
The contents of this book are so interesting and the throughline of the narrative just feels so incoherent compared to it.