>>280906881
It was a giant parasite, giants have been shown not to be much weaker than the tyrant bear so the giant parasite should be on a level close to a bear parasite, it also probably infected everyone who fought that giant and that probably allowed the parasites to take them over even after death.
And imagine if the giant parasite absorbed the bodies of the other dead giants, that would make a super wurm much worse than the one defeated by Yaotsu.
Just look at the pile of corpses of giants near him waiting to be absorbed.