What you"see" is irrelevant. Science says it's a human life.
Your shortsighted qualifiers, such as level of brain function, do not hold water in any other applicable scenario. IE - if you walk into a special needs facility and kill a mentally handicapped patient, even an extreme case that is completely incapable of any basic function, you will be charged with murder. Only on the altar of "women's rights" do we conveniently ignore these precedents.
There are questions here that science can't answer. When does that human get to drive a car, go to school, vote, etc.?
If a human being has no higher function brain activity and requires a ventilator, and I am that guardian of that human, I can legally choose to stop feeding that human or remove the ventilator. Perfectly legal. Only on the altar of "pro-life" do we conveniently ignore these precedents.