In a professional context, common terms for what you describe would be transparent, self-evident and intuitively obvious. (The last of those could be regarded as strictly tautological, but in professional circles it emphasises, for example, the idea that it is not hard to grasp a given detail of policy if you understand the structure around it.)
Again, speaking as a professional, the crux of this point seems to be not so much professional terms for ‘obvious’, but the statement ‘but for me they are completely new’. The sense here, and the thing aparently not being provided by HR in this case, is that non-specialists naturally require guidance.
If you put it in that kind of form, then you are no longer saying that you lack understanding: you are now saying that as a professional outfit it is HR’s duty to make sure that it provides understanding to its clients and others by making clear in its policies what it is talking about, and why.
With such ideas in mind, you could adjust the emphasis of your statement to something like:
HR people discuss HR policies with each other on a daily basis, and so for them those policies and their implications are intuitively
obvious. Naturally, however, non-specialists do not find these
elaborate professional structures transparent. They need the experts’
explanation and guidance.