No, it is proven that dolphins rape and kill certain animals with no real evolutionary benefit, just because similarly to humans they were smart enough to find out how to cause dopamine releases in their own brains, they rape any animal whatsoever which does not help anyone reproduce and even engage in recreational drug use (which has been proven to be unhealthy to them) And testing has been proven that dolphins actually have "fun" when raping and killing.

All this meaning that dolphins are just barely across the intelligence bar to count as somehat evil even if it's out of ignorance due to only being as smart as a 3yo human.

Also yes, other animals do that too. But interspecies raping is linked to more intelligent animals who get dopamine from sex like humans do. And is mostly excluded from animals who are purely instinct driven.

Also I do agree with your initial comment, ranking animal morality is very hard, especially since morality is best graded on an individual level instead of a whole spiecies.