Actually, it's cyclopes that are called giants. Cyclopeans are only ever called humanoids.
That is incorrect. Here are a couple of quotes.
"Known as Feral-Kind, these cyclopeans are violent and savage,
like many other types of giants." This clearly implies that they are in fact giants.
"As befitting their Giant ancestry, Cyclopeans have short, simple names." Again referencing their giant heritage.
Personally, I think that the author foolishly used the term humanoids to reference other creatures with a humanoid shape, such as Humanoids, Monstrous Humanoids, etc. Humanoid does have a meaning in the english language beyond the rules of creature types. If reading with context, that general English meaning fits perfectly in every place where humanoids are referenced. This would clear up why they are called out above as being giants.
Personally, for me the first quote solidifies the intent of what creature type they were meant to be.