One alternative that was popular what the steady state theory.

It assumed that the universe had always been more or less as it was now and would always be that way in the future.

This fell out of favor as we realized that the world and the stars above had not always been as they were now, and that things were changing over time.

There also were troubles with the fact that the night sky looked awfully black for a universe where stars were in every direction and had always been shining forever.