I don't think we are the only intelligent way of life in the huge universe. That is very difficult to support.

Many years ago I spent a few hours looking at a documentary called "The theory of ancestral aliens."

And I don't think all the casualities that the ancient world left.

Example The pyramids, as it is possible that even in this century, it has not been possible to explore the entire area and that no one can still argue in a solid way as it is built, it is magnificent masterpiece.