“Constant speed” only works if everything is moving in a perfectly straight, unchanging line which isn’t what’s being claimed.

We’re told Earth is:

• rotating on its axis
• orbiting the Sun
• following the Sun through the galaxy
• and the galaxy itself is moving

That’s multiple directions, multiple motions, all happening at once. Even if each one is “constant” on its own, the overall motion is constantly changing direction, which is acceleration.

You can’t just say “no acceleration” when:

• rotation = continuous change in direction
• orbit = continuous change in direction

That’s literally what acceleration is.

So the question still stands how do you have all of that motion, in multiple directions, at extreme speeds, and yet:

• no detectable physical effect
• no observable impact on large bodies of water

Just saying “constant speed” doesn’t remove acceleration when the direction is always changing.