I was doing primarily go development since it was first released up until a few years ago when the pandemic allowed me the opportunity to move into a full time remote gig doing primarily Java development, so I can answer this as I hadn't done Java at that point for over 10 years, so I felt completely new (what Java I did before that, I was mostly trying to not use Java by using play framework or jruby on rails)

As someone in the boat you mentioned (sort of) the short answer is modern Java development for 90% of tasks is not complicated at all: it's very much like any programming language used in a bizdev/corp environment -- you are mostly using a framework and a bunch of DSLs. Almost everyone uses Intellij and Gradle for IDE and build, and Junit5 or Spock for unit testing. I passed a technical interview mostly on Spring Framework concepts knowing almost nothing about it, nor having ever used it in production by simply just having the documentation open while I was being interviewed so I could look up the answers. Any language that is popular is going to have frameworks with decent documentation that help you be productive quickly, so I just jumped in doing Spring. The java stuff came as needed, or I referenced something like Effective Java (great book), or a Baeldung article. Java world has made some great strides since the 2000's and early 2010s of XML chaos. It took a while, but I feel like it's in a really good spot and getting better.

As an aside, if it hasn't been mentioned to you before, if you like simplicity in a language, but still incredibly productive, you might enjoy Go.