How much _individual rights_ it has. Humans have rights (unless they forfeit them by being criminals, killing in self-defense is OK & hanging Hitler would be perfectly fine).
Rights do not apply to animals because they have no capacity to reason.
Very small children also have no capacity to reason. There's also some levels of mental disability which keeps humans at lower levels of function than many animals.
Full context: A new-born has the right to life, but not property etc (can't grasp the concept). The parents are the guardians. When the child develops it gains full individual rights. People with mental disabilities also have guardians. They might not develop, but have rights.