So in the spirit of trying to learn more on the topic I did some online research and came across this
) which is not only pretty comprehensive but additionally seems somehow instinctually correct to me.
I have used the same website a few times in the past, it can give some good suggestions about what something could mean. It only 'works' insofar that we share metaphors with each other. Metaphors are personal, but we all happen to share a reality that naturally makes us have similar experiences, and being part of the (mostly) same culture also gives a lot of weight to having shared metaphors through dreams.
It can be a good exercise to look at some of the dream dictionary, and come up with a reason for why
that is, why does that metaphor mean this for me? Also look for metaphors that are different
for you, why is that? For example, I clicked on random letter, and got the list of "F". The top word is the letter "F", and it says: "To see the letter "F" in your dream symbolizes failure. It may also denote an expletive as in "F you"." This doesn't really apply to me, because we don't use the F-A letter grading system in my country, we use numbers instead.. so I have no personal experience that creates a connection between 'failure' and 'F'.
Another example I found: "Native American: To see a Native American in your dream represents the instinctual and uninhibited aspect of your character. You desire more freedom from cultural and society restraints.", that's probably true for most people non-native Western people, because we have experiences (mostly from films and books and such) that can create that connection, but for a Native American it would probably mean something different, because they would have a different experience and association with that word and concept, for them there would be wider range of meanings, which includes it having no particular meaning (because it's completely normal), to it having the same meaning as most people (though more direct).
It's essentially just suggestions, that best fits with the "idealised average person" within our culture.
Personally I wouldn't recommend that people focus so much on interpreting dream symbols, it can easily lead to over-interpretation and making an intellectual exercise of something that is often not intellectual. Rather just examine the intents and feelings in the dream, and take notice of 'decision points'. If you can't examine any of this, I would say that just looking at what it means for you to carry books (or any other 'action') is not of any real significance in terms of learning something new. It could be valuable if it's part of the path to looking into something deeper, or part of developing a greater interest in dreaming and personal growth, but just by itself, interpreting the examples you gave without an awareness of intent, feelings and decisions, makes it unlikely to have value in terms of personal growth.