What is the ruling on sitting on sacks of rice and barley and cartons of oil and food in general? Does this constitute a disrespect of blessings? And what is the ruling on workers throwing them or them falling to the ground?

It is not permissible to degrade food or do anything that compromises its respect, for it is a blessing from Allah that necessitates gratitude. However, carrying food in containers on animals is not considered degradation, and there is nothing reported from the scholars that prohibits it.