Everyone and thing comes about becuase of a cause. Aliens could not have “evolved through completely natural purposes”. (This in no way means I believe in aliens, but I am just continuing your analogy).
In the end God would have to have at least guided the aliens evolution, though I would say that if here were aliens more like he would have ‘created’ them through miraculous supernatural power. I don’t believe in aliens, but I do believe mankind was created through miraculous power.
Evidence exists in God being our creator, and the worlds, there is no evidence for aliens.