This is a controversial opinion but I think that an introduction to philosophy should probably focus on commentaries and summaries of the great works rather than the original source material. This is stems from a general point about education that it is usually easier to absorb knowledge from a text book that summarizes research than to get it from the original research itself. Philosophy as an academic discipline is…
On the other hand reading original sources gives you more than a summary. The way of thinking leading to the idea or the way the idea is presented is often more interesting than the idea itself.
Take Platon for example. The way he teaches his ideas in dialogue form is very pedagogical. It is even used in psychology [0].
An other example is Freud. He uses a very genius style of logical reasoning. Reading a summary of his ideas doesn't help you because you'll probably not understand it (and think it's nonsense) and sometimes he is just wrong (e.g. homosexuality is mental illness).
[0] https://en.wikipedia.org/wiki/Socratic_questioning#Psycholog...