I consider AI safety to be the primary overwhelming cause area in Global Health and Animal Welfare. But I think that even considering saving the lives of all human and animals doesn’t begin to recognize the scope of the issue. This is about extinction. So you must also consider the moral weight of all the future lives lost. I think also that considering life from a hedonistic standpoint of enjoyment/suffering, as if it could sum to a total and thus judge the life worthwhile or not by the total is fundamentally incorrect. I think it’s super weird that so many people commenting here are taking that assumption seemingly for granted without even acknowledging the assumption. Is not a life which has a few moments of glory, perhaps leaves some lasting creative achievement, but has a sum of negative hedonistic experiences, a life worth living? Would you say to someone experiencing chronic pain that you were going to murder them because you believed their life was net negative since they were experiencing more suffering than pleasure? This seems nonsensical to me.
Furthermore, extinction brings up an additional moral point. I place fundamental moral weight on diversity. Loosing an endangered species seems worse to me than loosing a similar number of individuals from a very populous species. Every extinction event seems far worse to me than the suffering of individual animals of the same type. If I had to agree that every elephant would live a net hedonistic-negative life for the next three generations of elephants (and that after that they’d still have to take their chances of leading hedonistic-negative or hedonistic-positive lives), but that this was the only way that elephants would get to continue to exist as a species… I’d absolutely choose for elephants to keep existing. This is separate from issues of hedonistic valence. I don’t value a plant species less or more because it can’t feel pain through animal nerve cells. This is a separate issue entirely!
Furthermore, I place value on another separate concept: complex intelligent perception of the universe and the related qualia/ experience. To me, the Universe would seem a much poorer place with no human left to observe it. I’d rather have humans exist, in net negative lives according to their selfish perception of suffering, than for no humans to exist. Animal species and plant species too, bring some value.
Furthermore, there is additionally the concept of future potential species which don’t yet exist. Uplifted animals. Digital persons. All these things add to both the fundamental values of Diversity and Experiencing the Universe. If all multicellular life on Earth were wiped out, but single celled organisms remained, I’d take value in that beyond the value I place in the lives of those single celled organisms and also beyond the value I place in the existence of their species. My additional type of value would be related to hope that someday multicellular life would evolve again.
Yes, the more complex take on the issue is to extrapolate. You can extrapolate the limited awareness of the chicken will never expand. You can extrapolate the child could grow into an adult who cared about their life in a rich meaningful way. Furthermore, you can extrapolate that this adult would be part of the category of individuals with whom you hold an implied social contract, and thus have a duty to respect and protect.
Also, see my other comments elsewhere on this page for more disagreements with your view.