I chose to save the human as the prompt didn't set a bar for the level of sentience. Also partly because of shameless speciesism. I love animals, have gone mostly vegetarian, but I would still save a human over any other animal.
Lots of animals die due to our existence and not just for our food. We accidentally kill things all the time with our vehicles and the pollution we cause. I wish it wasn't the case but you can't step outside without ruining some ants day.
To then be faced with a choice between killing one more animal or a human... my heart would bleed for the monkey but to do anything else would be murder and pretty hypocritical unless one lives an extremely vegan and eco friendly lifestyle.
No medical issue will strip away the fact that it is a human life. I'll make it more absurd for you... they could have a terminal disease and likely be dead tomorrow and I'd still choose to sacrifice the monkey to give them 24 more hours.
Or equivalently, would you sacrifice a billion humans to save a robot that's twice as sentient as the average human?
brain damage: now there's a hard one
That’s actually a very good point, I made more assumptions than the text gave cause for.