What was the most important discovery in astrophysics?

Neil deGrasse Tyson claimed in this video that "the single greatest gift astrophysics has brought civilization is the discovery...that the elements on the periodic table...owe their origin to thermonuclear fusion in the cores of stars," and that the supernovae of those stars lead to the creation of other star systems, including our own.

I don't think that is that is the greatest gift of astrophysics. If I'm wrong about that I'm curious why I'm wrong.

Edit. I am wondering if the cosmological redshift might be more important. Without it, and assuming we still believed the Steady State Model, wouldn't deep space observations would be very confusing?