The basic animal righton position is that moral regard should not be based on any characteristic alleged to be uniquely human but instead be a general compassion principle using sentience - a basic interest in living, avoiding pain, maximizing pleasure - as the standard by which we determine the moral worth of others.
This effort to extend moral concern beyond humans rests upon the other person sharing the same sense of compassion and agreeing that the uniquely human traits (real or imagined) that are often considered praise-worthy are in fact insignificant when compared to this alternative criteria.
Animal righton advocates spend a great deal of time defending their position from criticism, which is peculiar when they are the ones seeking to change the status quo.
There is an easy way to make a strong case for nonhuman righton without using sentience as criteria. It is a "Golden Rule with force" argument that shifts the burden of proof to the person who opposes nonhuman righton. The stronger their opposition to it, the stronger the requirement to prove their pov is true.
It should not be a revelation to anyone that the fundamental issue in animal righton that always comes up in any defense of an exploitation practice is the delusional belief that humans have superior moral worth as a group, claimed as an absolute universal truth without evidence, which leads to grotesque double standards in moral conduct. This is how racism or sexism or religious intolerance works, and how we arrive at the situation where it is acceptable to torture innocent nonhuman lives worse than the most despised criminals. To treat them in ways that nonhumans do not treat humans. And yet, we associate the word humane with goodness and the word inhumane with evil.
This superiority belief is not, as some assume, a biological instinct. If that were the case we would not have homicide or child abuse or war or even be having this conversation. How could we when human moral supremacy is an absolute universal truth? Something beyond all doubt or questioning?
We won't call it speciesism because the word implies that it is analogous to racism and sexism, even though it is a fact that while a member of any race or gender can be racist or sexist or both, only humans can be shown to be "speciesist," according to the definition of believing in the unfair and unjust superior moral worth of humans. If you call it speciesism you invite the dumb defense that lions and gazelles are speciesist too even though they can easily be shown to engage in violent behavior for survival purposes and cannot be shown to hold to moral codes that invite the accusation of a double standard.
A myth in human moral supremacy is taken for granted and left unexamined. It is like Manifest Destiny or a Chosen People myth. Incredibly, animal righton campaigners, even academic philosophers, tend to overlook this themselves and not consider it an essential part of the problem. They talk about sentience, or suffering, or the importance of compassion, but overlook this basic would- be-laughable-if-it-didn't-justify-hell-on-earth delusion.
When discussing racism or sexism, we are quite aware of this issue of arrogant self-importance. We understand what "white Christian supremacist" means, or "male supremacist," but when we say speciesist we are using a polite euphemism instead of being blunt.
Consider the absurd hypothetical demands human righton extremists and supremacist bigots make on campaigners for nonhuman righton. They ask them to choose who we would save in an emergency situation involving a human and nonhuman. They don't consider the consequences of such a scenario if changed to an entirely human predicament. If you have to choose between a familiar human and a stranger, does your choice determine which one deserves to be systemically exploited in a lab or farm? This is a double standard that exists entirely because of the blind acceptance of human superior moral worth even though the universe doesn't validate it and supposedly supreme deities are conveniently mute and invisible on the subject.
Or they demand that an animal righton activist be perfect - divorce themselves from society by magic and live on the moon, or be guilty of hypocrisy (a word very often misused). Such a demand is not made of a human righton activist - they are not expected to have not participated in society where things they oppose have happened. They can be against war and homicide and still live on land taken in war - they can use medicine that was lethally tested on slaves, prisoners, mental patients or African villagers.
The human supremacist bigot is often a bully - they want to browbeat the advocate into submission. Thus we have insecure activists who buy into the idea that humans have an instinct for choosing humans over nonhumans even though we know that this is a complete absurdity every time we look at crime news, or lock our door at night, or see a bottle with an anti-tampering cap, or smile in agreement at an ad that says: "the more people I meet, the more I love my cat."
This belief in humanity's superior moral worth is not scrutinized - if it were, it would become obvious that human superior moral worth is as much biased personal opinion as an argument to defend racial, gender, or religious superior moral worth.
The criteria cited to prove human supremacy include mind, intelligence, soul, creativity, Divine specialness, Evolutionary specialness, survival of the fittest, moral reciprocity, or an unspecified faculty X. They are all as much subjective personal opinion as the importance given to skin colour or gender or a particular interpretation of scripture. It either cannot be proven that all humans possess this supposedly important quality or that all nonhumans lack them. And Nature does not confirm this alleged superiority through natural phenomenon like weather, gravity, earthquakes etc. and the constant routine natural exploitation of humans by other humans.
Humans do not serve a stewardship function like worms or bees - the world would be fine without them.
If the world lost worms and bees, life systems would collapse. It is no surprise people have to claim an invisible mute deity or deities has ordained humans superior in moral value even though we have countless examples of humans slaughtering each other in the name of those same deities due to differences of opinion on religious trivia.
So much for the "rational" animal.
Ultimately, the moral argument against human supremacy is: if you want human righton, you must have nonhuman righton if for no other reason than to close a loophole that would allow humans to justify exploiting humans. There is no way around this problem.
If you claim humans can justify the systemic exploitation of nonhumans based on biased personal opinion (mind, soul etc) then another human can justify the systemic exploitation of humans using biased personal opinion since you cannot prove these opinions to be absolute, fair objective truth.
It is common sense that only humans can be shown to use moral codes and laws in an effort to control their behavior thus they are the only ones obligated to follow them, nonhumans benefit without needing to reciprocate out of fairness and consistency, since punishing them for being unable to follow human laws when you know they cannot would be unfair. It would be like punishing a blind man for not reading warning signs or an armless man for not grabbing a drowning swimmer.
Besides, nonhumans do not put us in cages, torture and kill us for choice, and other non-survival related activity. It may be argued that they already follow our moral codes. Criminals who we do claim can choose moral actions may deliberately violate such codes and are afforded far more compassion.
Moral perfection is impossible; you only do the best you can in any given situation. The failure to stop homicide or child abuse does not justify concentration camps, thus the failure to stop the accidental death of microbes or plants does not justify the construction and maintenance of farms or laboratories.
The simple truth of existence is that one is born, lives, and dies. During that time individuals will seek out survival-related interests and trivial past times. Success, failure, does it really matter in the long run? How can we prove that life is a contest or a race and if it is, where do the winners collect their prizes?
This is fact for humans and all life. If a single individual claimed they were superior in moral worth to all other humans and said this was a divine or evolutionary truth, we would regard such a person as arrogant or crazy or both. But when the claim is made about an entire species it suddenly doesn't appear insane (when it should).
Human supremacist bigots, anti-Nature fanatics, and/or human righton extremists are those who holds to a malicious deranged worldview where the universe and life exists as a play thing for a small group of weak and finite creatures, whining in protest when they are subjected to such treatment themselves, and boast of personal moral conduct and fairness that they do not live up to, unlike the very same species that they consider inferior.