How do you draw that conclusion? Certainly the Bible talks only about this one, but isn't it unwarranted speculation to arbitrarily limit God's power to also create other universes?
Fair question... Anything is possible I suppose but none of those ideas would seem to be consistent with what the Bible reveals about the character of God or consistent with the many passages of scripture for which the concept of multiple populated universes would have a bearing. Scripture lays out everything that is important for mankind to know and nowhere does the idea of another universe similar to ours show up. So, does that means that either such a universe doesn’t exist or does it means that God didn’t deem it important for us to know about? Based on the enormity of what is revealed, the latter would seem to be impossible. Consider the question from a broader scope (and related to this) is the idea that there might be a similar universe but without humans on it, or plant life but no animal life. However, dealing with a universe that has people on it would present such a huge theological problem that it would have to be discounted. As a ‘free will’ created and fallen mankind, God’s Son Jesus Christ was sent to die and to be the Saviour of humans.... if there was a similar race of people elsewhere and who had that gift of free will, that mean that Christ would have to die again .... and again and again depending on how many such universes were supposedly created. That just didn’t happen....Christ died once for the human race and that’s it. As for the possibility for instance of a universe that just had plant life on it, it would simply be inconsistent with many references to the fact that Earth is completely unique. Genesis 1:1 (KJV) ‘In the beginning God created the heaven and the earth.’.....it doesn’t say earths in the plural. The creation story says that earth was created on the first day.... it wasn’t until the fourth day that other interstellar objects including our own sun and moon were created. If there was going to be a belief that other populated universes existed prior to ours, it would mean that they would have been completely destroyed since our universe was created ex nihilo (out of nothing). That would mean that God made a mistake and had to start over... not consistent with the character of God. If God created populated universes after ours, that would seem to imply that he was hedging his bets on one of them turning out right... not consistent with the character of God.
I’m sure there are many answers to your question that are far better than mine but it is a Saturday and I must go and straighten out my garage... plus a lot of other things.