There’s no mention of lots of things in the Bible which clearly exist. It is not an encyclopedia.

I’m not saying aliens exist, I’m just saying that’s not proof they do not.

Jesus died in one specific place, but the effect is not just for that place, or even just for Earth. All of Creation is groaning, and all of Creation will be made new.

If aliens do exist, I don’t see how it’s any different than still-unreached human cultures existing.