Earth’s Inner Core is Around 1.15 Billion Years Old…So?

Perhaps I just have fine-tuned glasses when I look at the earth history.  Here we see a planet that developed a liquid outer core and a solid core.  Interesting that according to this release, the inner core formed 1 to 1.3 billion years ago. This article suggests  balancing to develop and maintain both cores.

Here is a quote from socratic.org. “With the heavy inner core, the earth's orbit and rotation will remain stable over the long term, giving us day and night and summer and winter. ... These swirling convection currents result in the earth's magnetic field which keeps us properly oriented for travel, and shields earth from deadly cosmic rays.”  It is vital for life.

I am sure that this had to be in place before the planet was ready for more complex lifeforms.    Intuitively, I would guess that this type of planet situation is very rare in the universe.