It’s what I derive from the fact that God made everything and He describes it to us in Genesis. Mankind is the only being that is described in the Bible as having salvation. The other beings do not have salvation. If another civilization exists, God would have had to create those other beings, and they do not have any provision for salvation, just like the angels have no provision for salvation.
When the angels sin, *that’s it* — they’re condemned and there is no way out for them. It’s the “end of the line” — with *no salvation*.
And for any other beings, since they have *no savior* (as only God can “save” and not any other created being, and there is only the Triune Godhead, of the Father, Son and Holy Spirit — hence no other ability for another “savior” to exist in the form of that other type of being in order to “save them” from their sin). When that other civilization sins — it’s *done for* with no salvation provided for them, just as when the angels sin, they’re *done for*, too.
In addition, if there are other beings who have been reproducing and growing into an advanced civilization, and finally traveling to see us here, I would imagine that they are going to feel very left out in that they will not exist with God and mankind, together, as it is described by God to us, and that they have no salvation (i.e., no provision for salvation as Jesus, the Son of God only died for mankind and not any other creation, which was why Jesus, the Son of God, became a “man” in order to provide for that kind of specific salvation).
God tell us about His messengers who carry out His will (the angels, along with the fallen ones) and they are there, along with mankind, but no one else is described as being there, after all is made new, at the end of Revelation (and also no one else is described as being there, when all things were perfect in the beginning (at the end of Day 6).
I can see the angels being required to be perfect, or just one sin and they are *never redeemed* and condemned to eternity separated from God in the lake of fire, to be tormented forever and ever. But, for an entire other civilization to exist without salvation and to “burn forevermore” in the lake of fire, for their sin — I just don’t think so...