The existence of an immortal soul is too controversial an issue to rest an ethical position on. Animals have some intrinsic value, but less than humans. Any basis for a difference will also rule out intrinsic value for some humans. It is wrong to use animals in science or in commercial agriculture. It is wrong to hunt commercially or for sport.
Philosophy is no substitute for action.
Everything with inherent value has rights which must be respect by other beings. Regan's position is non-anthropocentric. Regan's position is deontological. Regan's position is non-holistic. The rights of individuals are what counts morally, not the good or preservation of the community or group.