The idea of being “at rest” or moving more slowly than everything around you is pretty hard to pin down.
Consider the “inertial reference frame” which is assumed to exist (or an approximation of it) in order for Newton’s laws to function…
https://en.wikipedia.org/wiki/Newton%27s_laws_of_motion
Such a reference frame is said to not be accelerating or rotating. We pretend they don’t, for the purposes of solving various problems in Aerospace Eng. Aha, but these frames actually do accelerate and rotate! Just…kind of slowly, so we neglect the effects.
For instance, we might stick a 3-D reference frame (x, y, z) at the center of the Earth and align the 3 axes in convenient directions. But although the frame may be largely standing still with respect to distant stars, the frame is still moving in a circle around the sun, that means it is accelerating (centripetal accel.)
Ditto for a sun-centered inertial frame. The sun is moving around the center of the galaxy, hence it is accelerating too.
And our Galaxy is moving with respect to other galaxies. How, then, can we pick a point that is truly at rest? Maybe we just point to something that’s not accelerating or spinning that fast (once / day or once/year or once every galactic rotation) and say “it’s assumed to be standing still!” and… good enough.