I fear that this is really getting off track for the main and this might be in response to the wrong comment but is it really that surprising? (sadly)
In another comment of yours you mentioned choosing a pet or a random child? What about another, supposedly easier question, which would you prefer to save? A human life or $23? $23 might seem arbitrary but I picked it from my personal experience with a charity I volunteer with called ICM. It helps those with ultra poverty in the Philippines and I've had the great blessing (and curse) to undertake a tragic trip to the slums to meet these people. So I know the best I can offer is mine and ICM's word but that really can save a life.
I want you to know I don't bring this up to try and start a fight or be argumentative but this question plagued me when I returned home and to some extent still does. How can I buy a video game (random example), knowing that money I've just spent could have saved a life?
How do I, how do we, live like this? I'm an Australian and statistically, we're only giving less with each passing year, and what we do give? As on 2016 a measly $764. For comparison our minimum weekly wage is about ~$670. The least able of us (that are able at all) would only have to give a little over one of their weeks to match that.
Personally I'm the sort of crazy where I think of this almost every time I make a purchase and for the longest time it was killing me. The TL;DR of how I was able to answer this for myself involves a lot of reading, looking and thinking is basically summed up as follows. For most normal humans (myself included) we need to spend on ourselves to make us functional enough to care for others. We are sadly not infinite source of giving.
However I think society today has forgotten or changed enough that we no longer see this self healing as a means to enable us to help others but as the point of living, hence the ever decreasing percentages of people giving but I still have hope.
I'm sorry at this point I don't know exactly where I'm going with this at this but it's not that people value animal life above human life, it's that they value their own life and quality of life above others and as sucky as that answer is, I hope you find it help answer your questions in a manner that makes more sense.