> How would we feel if aliens stopped the mass extinction events that led to our existence?
This statement is just appealing to emotion and is commonly used in arguments against abortion or attempts to thought police. There is nothing provable or disprovable in your argument and this question is used to just try and bait people into an emotional response.
> Non-human life seems by and large indifferent to its long-term fate on this planet.
I would argue that self preservation is an innate characteristics of every plant and animal on this earth. Isn't a desire to live the basis for self preservation? Isn't it natural for a plant or animal to stop something from killing them if it impedes in their ability to survive? At a basic level plants compete for sunlight at the expense of other plants. If there was an cognitive leap in a plant or animal wouldn't it be natural for anything to protect their greater habitat? If that's narcissistic than I guess it's the most natural narcissism I can think of.