It's a simple question. Is god going to somehow make amends for animal pain and suffer? We now know beyond a shadow of doubt that animals are sentient and capable of feeling pain.
Therefore the question is simple. Will there be gratification of some sort for all those creatures that already died?
If the answer is "No" it means that god deliberately created creatures to let them suffer and then annihilate them without gratification. It's obviously true when we consider all these poor animals which were born with severe defetcs turning their lives into nightmare.
If this is the case then god isn't good. Knowingly designing things in a way that cause them to suffer so much isn't compatible with any sort of morality.
And if the answer is "Yes", then my question is this: In which sense? If animals don't have soul of some kind, it follows that after they die there is no being on which god can exercise his good or justice so how is it supposed to work?
You seem to be calling for a new scripture out of thin air, for none of the religions address this question. Indeed, there isn't a solid teaching about the human soul anywhere to be found, for you to reason from there to a question about animal souls! Anything said about souls has been totally vague. The Christians are found mingling ideas of soul with ideas of body, not even sure what they want.
The former scriptures have come as stark unsupported statements that today's generation seems to accept because the older generation did, but we can probably reason about this question. Let me present a tentative scenario, though it may bend Christian ears to uncharted territory. We know one of the traits of the animals is an inability to care for their own habitat. For instance if you put cows in a pen, they'll eat or trample all the grass until they're shin-deep in mud. They await the farmer for a better situation.
In can be argued that in overpopulating the planet and failing to preserve precious resources for the future generations who will need them too, humans share this aspect with the animals, inability to maintain their habitat, which happens to be a planet in this case. Well if you look in Hindusim and Buddhism, this is already the teaching, that the souls are on an upward journey from animal states.
In that type of scenario it can also be observed that animals have no conscious fear of death; and that humans seem to have a fear but it doesn't have much result, otherwise the planet would be covered in monasteries. If you next consider the tenets of these religions that there is a state of enlightenment or nirvana toward which the souls tend across their births, it next becomes apparent that God, if He made the souls, created them with ignorance about death as well as the exuberant life of the spirit such states eventually convey (or again, the planet would be covered in monasteries as people try to attain these).
It then appears to be God's act of mercy, that the animal souls would not have self-awareness as spirit, and that their spiritual evolution amounts to the awakening of this awareness. In other words, neither the animals nor the humans are suffering very deeply in a spiritual sense, over death or some of the physical suffering that can come, though this is painful to their senses for a few hours or days. If rebirth is reality, then God is forever bestowing new life to all these suffering creatures, plus the blessing of not recalling their suffering from a former situation. I think this “hypothesis,” addresses the questions.
