So what, even if demons created them. That's not a biblical sign of the times.

Nothing in the Bible about crop circles. Nothing about demons being able to make stuff on earth only shortly before the end. Nothing.
So we can be easily thousands of years before the end. And that is likely. After all, the Bible speaks several times of one thousand generations. That will end thousands of years from now. A generation is at least 20 years. So I don't think we are only a few years from the end at all.