If scientists ever discover any alien life on other planets or here on earth (after traveling from their home world or galaxy), it would necessarily mean that God did in fact create other forms of life, and we would know this by using the same logic we employed to deduce that the human race had a Creator. Aside from the characters portrayed on Star Trek or Doctor Who, we have no idea what intelligent alien life would look like. It could be humanoid, or it may not be. The big question is whether or not extraterrestrial aliens would have immortal souls.
Human beings have souls because the Bible tells us that we are made in the image and likeness of God. God is a pure spirit and has no body. Jesus took on a human nature and a human body when He became our Savior. The human body in and of itself is distinct from the soul. Human persons are a union of a body and a soul. Intelligent or rational alien life could be in the form of physical bodies which do not resemble mankind in any way, shape, or form, but if the creatures have intellect and free will, it would be a safe guess that such beings might also possess immortal souls.
If intelligent life is ever found out in the recesses of the universe, evangelization (sharing faith) would not be an alien concept since many have done it before with alien cultures though not yet with alien species. God has a divine intellect and a divine will, and mankind has a human intellect and a human will. While people are made in the image and likeness of God, it is not their human bodies but their immortal souls that are in the image of God. The body is not incidental, however, since Christianity firmly believes and teaches the resurrection of all the dead at the end of time.