Why were the bodies of the Jenin camp martyrs decomposed and foul-smelling, despite what is heard about the earth not consuming the bodies of martyrs and their scent being like musk?

The correct view is that the martyrs are alive with their Lord, sustained, fed, and enjoying bliss. This is what distinguishes them from other believers. As for their bodies not changing, there is no evidence for that. The scent of musk will be present on the Day of Resurrection to demonstrate the martyr's virtue, which is why the battlefield martyr is not washed. The decomposition of the bodies of those who were unjustly killed in the Jenin refugee camp does not negate their martyrdom, for whoever is killed defending his property, blood, or family is a martyr, regardless of whether his scent changes or not.