Zilch. The existence or lack thereof of sentient life "out there" has as much relevance as did the existence of human beings in North America to the early Church. Which is to say none at all.
An excellent analogy. That the Prophets, Jesus, Apostles, Fathers & succeeding Christian generations did not so much as suspect the existence of the American tribes, of the Amerindians, of the Japanese, or of the Maori, does not affect, let alone invalidate, the Christian revelation.
The Universal Kingship of Christ is not invalidated by ignorance of its existence. If that applies to peoples on Earth, why does it not apply with equal force to whatever creatures may exist on other planets.
Supposing there are Romulans, & that they are in need of salvation: why can the salvation worked by the God-man on behalf of mankind, on Earth, not avail for Romulans as well ? After all, the saving work of Christ is supposed to be of infinite worth and power, so as to be sufficient for a trillion worlds, supposing them to exist & to need salvation.
And does the Work of Christ as Renewer not extend to all creatures on Earth ? If lions, lambs, serpents, birds and other, Earthly, creatures are beneficiaries of the Work of Christ (as Romans 8 & Isaiah 65 seem to suggest), then why should creatures on other planets - supposing them to exist - not also benefit from it ?
In a perfectly renewed creation, will not non-human animals be as fully restored from the "futility" & sin that presently wounds creation as fully as mankind will be ? Surely an adequate doctrine about God's creation needs to have room for the entirety of what God has created, and not for men and angels & Earth alone.
If the Three Holy Children in (deutero-canonical) Daniel 3 had known about neutrinos or supernovae, they would presumably have called upon them, too, to praise God; as would the Psalmist in Psalm 148.
The Song of the Three Holy Children AKA the Benedicite:
Benedicite, omnia opera.
O ALL ye Works of the Lord, bless ye the Lord : praise him, and magnify him for ever.
O ye Angels of the Lord, bless ye the Lord : praise him, and magnify him for ever.
O ye Heavens, bless ye the Lord : praise him, and magnify him for ever.
O ye Waters that be above the firmament, bless ye the Lord : praise him, and magnify him for ever.
O all ye Powers of the Lord, bless ye the Lord : praise him, and magnify him for ever.
O ye Sun and Moon, bless ye the Lord : praise him, and magnify him for ever.
O ye Stars of heaven, bless ye the Lord : praise him, and magnify him for ever.
O ye Showers and Dew, bless ye the Lord : praise him, and magnify him for ever.
O ye Winds of God, bless ye the Lord : praise him, and magnify him for ever.
O ye Fire and Heat, bless ye the Lord : praise him, and magnify him for ever.
O ye Winter and Summer, bless ye the Lord : praise him, and magnify him for ever.
O ye Dews and Frosts, bless ye the Lord : praise him, and magnify him for ever.
O ye Frost and Cold, bless ye the Lord : praise him, and magnify him for ever.
O ye Ice and Snow, bless ye the Lord : praise him, and magnify him for ever.
O ye Nights and Days, bless ye the Lord : praise him, and magnify him for ever.
O ye Light and Darkness, bless ye the Lord : praise him, and magnify him for ever.
O ye Lightnings and Clouds, bless ye the Lord : praise him, and magnify him for ever.
O let the Earth bless the Lord : yea, let it praise him, and magnify him for ever.
O ye Mountains and Hills, bless ye the Lord : praise him, and magnify him for ever.
O all ye Green Things upon the earth, bless ye the Lord : praise him, and magnify him for ever.
O ye Wells, bless ye the Lord : praise him, and magnify him for ever.
O ye Seas and Floods, bless ye the Lord : praise him, and magnify him for ever.
O ye Whales, and all that move in the waters, bless ye the Lord : praise him, and magnify him for ever.
O all ye Fowls of the air, bless ye the Lord : praise him, and magnify him for ever.
O all ye Beasts and Cattle, bless ye the Lord : praise him, and magnify him for ever.
O ye Children of Men, bless ye the Lord : praise him, and magnify him for ever.
O let Israel bless the Lord : praise him, and magnify him for ever.
O ye Priests of the Lord, bless ye the Lord : praise him, and magnify him for ever.
O ye Servants of the Lord, bless ye the Lord : praise him, and magnify him for ever.
O ye Spirits and Souls of the Righteous, bless ye the Lord : praise him, and magnify him for ever.
O ye holy and humble Men of heart, bless ye the Lord : praise him, and magnify him for ever.
O Ananias, Azarias, and Misael, bless ye the Lord : praise him, and magnify him for ever.
Glory be to the Father, and to the Son : and to the Holy Ghost;
As it was in the beginning, is now, and ever shall be : world without end. Amen.