We need not debate the time frame of creation with today's scientists, whose own theories are very much in flux. The crucial point is that Judaism insists that God authored the universe, created its orderly systems, and continued to be involved in every aspect of creation, phase by phase. The argument from design is very persuasive on a common-sense level. But we often wonder why God does not speak even more clearly about His existence, to reassure us at least that He is present. In ancient times, it seems, people saw miracles and heard God's voice, or at least knew people who were clearly connected to the Divine force, like prophets.
Humanity is, in a sense, an experiment.
When God created Adam, He made a being who could decide whether to be like the rest of creation, acting on an animal level, or to be like God Himself. The crux of the human experiment, the one independent variable, was that we should have free choice. If miracles were commonplace and the Divine Presence was indisputable, humans would have no choice but to acknowledge God. It would be as if we were compelled to believe in God. Miracles did happen long ago, because they were needed to demonstrate God's existence to a world that had no concept of God at all.