Usually we say that we 'have' a body than that we 'are' a body. Essentially we are human beings but is it wrong to deny that we are bodies according to Thomas?
According to the well-known Aristotelian definition, humans are "rational animals", i.e. animals (with body) with intellectual faculties.
Considered as a substantial form of a material body, the soul exists in a living being as the substantial form of an animal.
Humans are substances, made of matter and form. The living being is the human.
There is no "modern" self that "owns the body".