EDIT: If you prefer my take on this to John C. Wright's, what's wrong with you?
Being the devotee of science fiction that I am, I've given thought as to whether aliens would have human rights. The reason humans have rights is that we are made in the image and likeness of God. At least one SF author suggested this means humanoid form (i.e., bipedal, two upper limbs for manipulation, binocular vision, etc), but I don't buy that, because God, both as Father and Spirit, has no form whatsoever. So what does "image and likeness of God" mean?
Well, what are the most significant things we have in common with God?
God is Love. By this, I mean that He wills and seeks the greatest possible good for His beloved. We love in this manner also, and it's considered a very serious defect when a human is not able to love. So aliens, to have human rights, ought to be able to love, and hopefully they normally would love.
God is creative. "In the beginning, God created the heavens and the earth." Certainly we echo this aspect of His being, and create things all the time. It is this particular lack that convinces me that cetacea are not human, and don't have human rights: they do not create.
And finally, God is rational. He never contradicts Himself. Reason is a means of learning the truth, and it is a gift from God. Far too much of our doctrine is arrived at by reason for us to discard it as not from Him. An alien race not able to use reason would not have human rights. I think that this would include language; if you can't communicate, or think symbolically, I don't think you can reason.
The next question that any Christian would have to ask once he discovered another race made in the image and likeness of God would be, "Do they need salvation?"
Do they sin? We misused our freedom to disobey God, and are still suffering the consequences. They might have never made such a mistake, and might even avoid following our example once they meet us.
If they do sin, has God have provided a savior for them? Or, was Jesus' sacrifice enough for only Earth, or for all of Creation? The former suggests its insufficiency; the latter imposes some really intense problems in travel and communications technology for us to overcome. Both do sort of suggest that the entire universe does exist for us. THAT is reason for some profound gratitude, as God had no need for us or any of the rest of it. It is not waste, however; God has no limits on His resources, after all. He could have even made the infinite multiverses that atheists propose entirely without any evidence beyond the need for more time for a universe so improbable as to support human life to arise.
Regardless, it's only a matter for idle speculation until such time as we meet such extraterrestrials -- if we ever do.