Well @theironfelix said pretty much everything there can be said on the way the religious would receive it . most Pagan religions would not change or be disturbed by it as "other realms" have always been a part of the general narrative.

As for the soul question if we have souls they will have them too ... if there is life after death and some eternal spark it lives in us all ...not only one species on an insignificant rock.

As for do the question if I believe that there is life out there, the answer i yes. i mean we already know that some asteroids carry the components of life and some even believe to have found bacteria from outer space (they just could not be sure as the samples were contaminated) . As for intelligent life it would be mathematically highly improbable if we were the only ones. the question is are they rock bound like we are or are they more advanced.

As for how they would look seriously anything goes. i mean look at the diversity of life on this here rock and quantify it by billions ...