if the things being used in a tutorial are completely beyond you then it is probably a bit to advanced for you right now. i would take a step back and learn other things until you gain a bit more experience and knowledge. you mention a inventory tutorial, thats a intermediate topic id say. i wouldnt go for that one until your familiar with blueprint communication.
if i were in your place, (and this is how i started out in UE4) i would do the intro to blueprints series. then once you know how to make things happen within an actor move on to the blueprint communication stuff and build a health system or a light that turns on when a switch actor is activated. simple things at first then build on it one node at a time and let the knowledge snowball until you can do it all.
another good playlist for beginners i think is the blueprint jumpstarts list .
the basic idea to learning programming and getting better at anything really just comes down to experience. learn something then build on it and adapt it to work in different ways.