Probably going to depend who you ask. My husband would say brown, I would probably say black. My husband is Mexican and so his perception of black hair is different. He called his own hair brown for a long time, but most Americans would say his is black. In some cultures like Asian and Hispanic where “black” hair is very common they usually look for hair to be very very black, sometimes we call it blue black, or even texture, like straight black, to be considered black, while in America we use the color black more loosely for hair color.
Interstingly, my husband’s family is much looser with the description of blond. Anything close to dirty blond, even what I would call light brown, is blond to them. Most Americans describe lond very specifically, blond, dirty blond, platinum blond, I never hear his family do that. In fact, his dad once asked why the mom of a girlfriend of his granddaughters, dyed her daughters hair at such a young age. They were 5 years old at the time. The little girl hat typical very blond, platinum, hair that blond children get when out in the sun all summer.