Don’t worry about it, Frank.
In a way, your question brings up an interesting aspect of this complex world.
Especially lower animals are more like robots, they just live “paying their kamma vipaka”, without the ability to do any strong good kamma or strong bad kamma.
This can be explained only in terms of the type of citta experienced by animals. So, I cannot provide a satisfactory answer without using Abhidhamma.
But here is a key point to remember. It is mainly humans who can generate strong kamma vipaka BOTH good and bad.
– Briefly, “ditthi sampayutta citta” generated by those humans who do immoral actions with wrong views generate the worst kamma vipaka.
– On the other hand, those who have comprehended Tilakkhana (and thus automatically generate “nana sampayutta citta” at least in some cases) generate the strong good kamma vipaka.
– When one progresses on the mundane eightfold path, the tendency to bad kamma (deeds, speech, and thoughts) will decrease. Then when one starts comprehending Tilakkhana, the tendency to do good kamma (with better understanding) will start increasing.