humans are more populous than cattle so the per pound cost should be lower
As of 13 years ago there were about 1.3 billion cattle worldwide. So humans outnumber them around 6:1. So humans would be cheaper based on availability.
However the average cattle (all breeds, both genders) weighs 753kg, whereas an average person is around 62kg (worldwide average).
That makes the average cow 12 times as massive as the average human. And cows have quite a high meat:bone:organ ratio.
So, there's some 980+ billion kilos of cattle, compared to 460+ billion kg of human on the planet.
So just by population alone cattle should be cheaper per pound than humans, let alone the cost of rearing a human to maturity, which takes 18 years of feeding and sheltering.
And human food is more expensive than grass for cattle.