I don't know that the bible doesn't leave room for it, though it is very true most 'believers' don't even want to contemplate it. You notice how much there is written in the bible that's a plateful to contemplate just as it relates to our places on the earth.
As for me, I believe God's big enough to make as many creatures and galaxies as pleased Him to; and when it was written 'in the beginning...' it may refer to 'in the EARTH's beginning...'; it DOES mention that he made all the heavenly bodies, so I can reasonably deduce that if there's life on THEM He's probably the cause as well. It does mention that 'sons of heaven' came to earth, which i find interesting, but i don't think anyone is really qualified to define that.
I would think that if He made aliens, too, and if they strayed in THEIR relationship with Him, he probably devised a plan for redemption for them like he did for us. But if they STAYED in perfect harmony with Him like Adam and Eve should have, then they're probably fine. Til they come here, of course, and we kill 'em all out of fear. but i suppose that's another thread. :)
As to 'what is he to the grey aliens', i don't think i am one, so not qualified to say. but am reminded of when one apostle asked Jesus 'what about the other apostle', was he going to be just taken up or die or what, and Jesus said to let it be his concern, not the apostle's. So maybe the best thing to start with is have we chosen to align ourselves with at least a mustard seed of faith in Him? and then go ahead more strongly with conjectures, cuz, like, what if tomorrow i died? all the wondering about aliens wouldn't get me closer to talking with him directly. imho.
Who exactly is in heaven? You've seen sunbeams come in shafts through clouds, right? and they're really glorious during a sunset? and you can almost feel the energy off them? i believe once our essences are released from our body shells we merge into that pure, unadulterated energy and light, being collected back to our source, and our energies are probably recognizable to those we've loved,because we may have started out as those energies to begin with before we were appointed our places in space and time. which might also account for those rare times when you meet somebody new but they're just like a best friend and you get along great from day one as if you'd always known each other.
hope some of this is helpful as food for thought, if nothing else. :)