Sure, the degree of something can remove it from a category. This can be within scientific categories and within everyday speech, and some of my examples were examples of this. I included when one is exposed to heat, which is what causes burns, but it is not a burn. The degree of the effects of the heat, if low enough, no longer qualify it, in medicine, as a burn. Further you have the assumption of your conclusion in your argument. Eating is, for you, some degree of slavery, so it is merely a difference in degree, hence it is slavery. Even if no one owns you and could sell you, you still want that to be defined as slavery. Having a need does not make one a slave, except metaphorically, perhaps. A drop of water on the ground is not a lake or an ocean. It’s not even a puddle.
Someone gently caressing my cheek is not slapping me, even if the movement is exactly the same only slowed down immensely.
The sun is not a red giant, though it is a star like red giant stars are.
Pluto is no longer considered a planet.
Normal blood pressure is not high blood pressure, which has its connotations of health problem.
A whisper is not a scream.
Tapping you on the shoulder (using the socially accepted degree of force and in the correct, pretty wide range, situations) is not assault.
Legally, medically, scientifically and in everyday speech changes in degree CAN AND DO shift categories.
Sometimes there are grey areas. And yes, differences in degree do not always entail different categories.
But, then, again, it often does. A gale is different in degree from…other windy situations.
A short person is not always a dwarf, due to degree of difference from average height.
Change the frequency of something and it can change category - ultrasound, now a difference color, now its microwave radiation…etc.
Bald. People with the usual amount of hair are not bald, even if they lose some hair, but lose enough, a difference in degree of hair loss, and they are.
And then you need to demonstrate that those things you are calling slavery are merely differences in degree rather than in kind. I don’t think you’ve done that.