Answer:
The "brother's keeper" story, as you probably know, is from Genesis. Cain kills his brother Abel and God asks Cain where Abel is. Cain asks God, "Am I my brother's keeper?" This is the murderer Cain's choice of words designed to force God into a response that would get himself off the hook. A keeper is not a "neighbor" whom the Bible does tell us to love. A keeper is someone who, like a zoo keeper, knows what is good for his animals better than the captive animals do. Cain only uses the phrase sarcastically because he knows God would have to answer "No."--if He answered the question. Loving and helping our neighbor should not be conflated with knowing what is best for our neighbor when the neighbor might not agree. God sees the trap, ignores it, and tells Cain that his brother's blood is crying out from the ground.
We're used to seeing language in the Bible that is archaic or poetic and we tend to interpret it as such. But the use of the word "keeper" in the Bible context means exactly what it would mean in everyday conversation today.
Nowhere does the Bible say we are our brother's keeper.
Now ask what it means to "Love your neighbor".