Why?
But still, having the single core version flying will allow them to test the engines reliability and reusability aspects for years before the triple core version files, which will hopefully allow the CZ-10 to be human rated a lot faster.
Don't see any meaning of your statement, CZ-10 is just doing the very routine job like all other crew rated rockets. CZ-10A flight is one of CZ-10 test flights. It is like sub-orbital test of first stage of a full rocket.
NO crew rocket is launched with human in its maiden flight ever. Saturn V had 2 uncrewed launches before put human on it. CZ-2F had 4 uncrewed launches first. During these launches, you either put dead weight or put some satellite to make use of it.
Even if the maiden flight is the full sized CZ-10, they will not put human on it, but could send the final design of the crew module around moon like Artimes 1 mission.
About the bold texts, I think you forget about the purpose of CZ-10. It's time plan is aiming for moon landing before 2030, that is a deadline. From maiden flight in 2026, there is no more than 4 years. There will be 3 uncrewed flights with crew module on top of it. Time is tight. On the other hand CZ-10A does not have a deadline because CZ-2F and old Shenzhou all work just fine. Realizing reusability of CZ-10A has a low priority. So either CZ-10 go first, or immediately (around a year or less) after CZ-10A, there won't be "years" for CZ-10A to prepare CZ-10.