@Chookie89
What has the (obviously grotesque) transatlantic slave trade got to do with it? Of course it wasn't founded on moral principle!
Try to read what people are actually saying. Can you think of any moral system (e.g. religion, philosophical argument) that argues that people are required to save someone else's life at extreme cost to themselves?
Don't we usually single people who do that out, as heroes? Some of us might jump out in front of a bus to save a child we didn't know. But no moral code I know of demands that. (Conscription in war is different. War isn't about trading one life for another and putting yourself second; we fight wars to win then, and justifiable wars are fought to protect basic principles (justice, democracy, not violating human rights) that we want to see endure.)
In the old world, I sometimes used to see apparently serious car or cycling accidents on my way to work. Passers-by often didn't even both to stop, even though it would only made them a few minutes late and they might have made a really significant difference. I once stopped to help a cyclist who was knocked off his bike and thrown (very luckily) across a major crossing, but who landed (no helmet) and cracked his head. I realized when I did that I'd forgotten to charge my phone. Eventually someone else came over and offered theirs. But most people didn't do anything.
I would argue that one's duty to stop in that situation outweighs (limited number of actors, highly time sensitive, potentially fatal injury, physical involvement as a witness, minimal sacrifice) vastly outweighs the duty to 'stay at home to save lives' (messy problem, chronic situation, clear individual and collective sacrifices). But obviously most people don't agree with me.