At the time of writing, OP had not made it clear which visa they had, and from their description, a business visa seemed much more suitable; I was trying to emphasize that point.
------------------------------
^^^
Suggests to bring a copy of the invitation letter, just to be on the safe side.
^^^
Also suggests to bring a copy of the invitation letter to be on the safe side.
^^^
Now states invitation letters aren't needed ----->
No worries; it's China: better be safe than sorry, and just because something is technically not needed, doesn't mean it isn't wise to "play it safe".
During the pandemic there were stories about foreigners getting asked to produce their work permit and apartment lease on entry, and although I never got asked for this in 15 years, I relented too, and took copies of them with me back in 2022, just in case. Wasn't asked for them, and don't bother to take that precaution anymore.
Like was written, it's just a matter of your own personal comfort level.