Final answer:
Olaudah Equiano is the enslaved person who wrote about the inhumane treatment of captured Africans.
Step-by-step explanation:
The enslaved person who wrote about the inhumane treatment of captured Africans is Olaudah Equiano. Equiano was born in what is now Nigeria and was later kidnapped and sold into slavery. After gaining his freedom, he settled in London where he advocated for abolition and wrote an account of his life.