“Going to take a lot of space for redeemed mankind to live an eternity...”
Interesting thought. And who knows how God will make eternity work? Not me!
But all of us tend to have a hard time conceptualizing how much space is needed for things. When my oldest son was in 6th grade, his teacher told the class that there would soon be too many people on Earth and we’d have no space. I constructed and sent her a spreadsheet which showed that if we divided Texas (dry land only) into typical classrooms, 7 billion people divided into families of four could all fit with (I forget) 70-80% of the classrooms empty. And that’s just one level with no upstairs...
Back to the eternity comment, as far as New Jerusalem goes, it will have plenty of room for all of God’s saved. But I imagine, like you, that we could be going in and out and doing a lot of traveling if we want! I’d kinda like to see other galaxies.