If you’re looking for a book about how human history has been shaped by microbes, and to some extent the evidence from microbes about our own development, this book is definitely going to be of interest. It’s not just diseases, though it does mention a lot of them; it does also touch on some of the more harmless microbes we’ve been carrying around. And of course, it talks about how we’ve shaped the evolution of microbes, as well.
If you’re a nut about this kind of topic, this isn’t very in depth and I don’t think you’re going to learn much from it. Something like David Quammen’s Spillover hits some of the same points while going a bit more into depth. But it’s a well-written survey of the subject, perfect for a layperson.