Any time you talk about speed, you need to discuss what it is relative to (unless it is clear from context).
A key part about relatively is that there is no preferred frame.
If you were to take 2 identical space craft, A and B, in an otherwise entirely empty void; and then have one of these (A) remain stationary while the other (B) accelerates to 0.999999999999 c and then continues at that velocity, and then place an observer in each, they would not know which one they were in.
The observer in A looking at B perceives itself, the craft it is in, and the other craft equivalently to the observer in B looking at A.
That is because what matters is relative velocity.
Relative to craft A, the observer in A is stationary, and craft B is travelling at 0.999999999999 c.
Relative to craft B, the observer in B is stationary, and craft A is travelling at 0.999999999999 c.
So even though craft B accelerated and reached that speed, to the observer in it, everything is normal and the "stationary" craft looks strange.
So with your claim of Earth travelling near c, the question is what is it travelling at that speed relative to?
Because it is only to an observer that it is travelling at the speed relative to that it will appear strange.
To a comoving observer, i.e. one on Earth, Earth will appear normal.
If you want to object to UA, a valid objection is the variation in g accross Earth.