What Einstein did not include was the motion that the Big Bang event put in place. Einstein did now know about the Big Bang when his relativity theories were published.

Later on, I think he double checked and noticed that it did not matter.

Matter is involved in four motions, but Einstein only included three.

1. Big Bang event

2. Galaxy rotation

3. Planets revolving around star

4. Planets spinning (moons in tow)

The Big Bang event is not based on gravity but on the force that propelled the onset of material motion (just once). When in place, this motion will not stop unless another force is applied to it (first law of physics).

Einstein: 3 Motions + Spacetime

Reality: 4 Motions

'Einstein, Gödel, and Me'

https://fred-rick.medium.com/einstein-g%C3%B6del-and-me-5bee14dd0edd