The effects of the eaten species only appear in the offspring. Looking at the queen, one could surmise its own mother, the previous queen, had eaten a human. Or perhaps already two or more generations ago because the leap from an insect to a thinking and talking humanoid is quite a big one. So, whether this particular queen had or hadn't eaten humans before wouldn't affect in the slightest its own countenance or mental capability (provided it had enough food in general to develop fully, which it did).
The next queen ought to be quite interesting, though. I have a feeling we might see it before Kite, Gon & Co lay waste to the whole colony.