I don't see anything wrong with this list. I've read the majority of works listed here and would say if you read all of these you'll be quite well read, but don't stop once you are done here.
Personally I've never liked classifying things as beginner, intermediate, or advanced and just read what I feel like at the time.
Sometimes it is also easier to read a few works in a row by the same author. For example you have Lenin spread in different levels but it might be easier to read those one after another since these authors do all have a bit of stylistic differences and when they are mentioning other people you won't have to look up the person repeatedly if they are fresh in your mind from their other works
Love it, it's rare to see Dialectical and historical materialism as an introductory text but it is completely correct and i regularly advocate for it. Dialectical Materialism is Marxism, and it is a crime against humanity hearing people claim they're Marxists but have no understanding of dialectics.
I'm not yet well read, but I'm currently reading more theory. I think Why Socialism? by Einstein shouldn't just be a honorable mention, it is pretty good as a first text to read, specially if you want to send to someone that does not know much about communism since it is such a simple text. I would add The Three Sources and Three Component Parts of Marxism by Lenin after The Principles of Communism by Engels helps a lot, it's a pretty short text that is very approachable.