I've been trying to learn about all of this stuff over the last couple of weeks, and agree that it isn't obvious. Designing Data-Intensive Applications by Klep

I've been trying to learn about all of this stuff over the last couple of weeks, and agree that it isn't obvious. Designing Data-Intensive Applications by Kleppmann has been helpful. It doesn't cover every framework, but I think it helps explain where a lot of the pieces fit together and when you might want to use some of them. I've also found it useful to find podcasts that explain specific projects, such as Apache Kafka, and listen to them when I'm running.