There is of course no correct answer to this question (although I’m sure someone will disagree with me). I’m a huge proponent of learning by doing. Work out what you’re trying to achieve and then learn what you need to do it, from whatever source works for you. Smaller more well defined goals work best for this I find.
The learning library is great for that, as is Youtube, but if you don’t have a set goal with what you’re trying to learn then as you said it is just simply too much information to take in and retain. But by doing lots of different little things with it you will eventually just kind of have that information stored to draw from. The documentation also contains explanations for almost everything that you’re looking for, if you’re trying to get down on the why of a thing, and also these forums are a pretty friendly place for the same.
The truth is while there are some pitfalls to be careful of with blueprint no doubt it’s pretty easy to make it work and then you can refine later if you need to. Having a fundamental understanding of C++ will help a lot too.
And when all else fails if you need a simple clear answer to what a blueprint function is used for specifically @MathewW_EG’s back catalogue on youtube has been a friend to every new developer beginning their journey with Blueprint!