Time is relative, just not to man.

What is time relative to then?

Newtonian mechanics is limited to the natural world obviously and Newton doesn't make claims about metaphysics. The problem with relativity and any modern "theory of everything" is that it rejects metaphysics on one hand but delves deep into it and tries to explain metaphysical concepts through physics (dark matter, ultimate nature of reality, the nature of time and space, causality beginning and ending of the universe, black holes). It has transgressed its limitations and went into philosophy and religion territory. This explains why much of modern science is tied to occult practices and movements like Thelema and theosophy (look at the origins of NASA and what Jack Parsons did).

Most scientismo spergs don't even realize this because they have zero knowledge of anything outside their field and think philosophy is a bunch of gobbledygook.

But I agree that general relativity can have some application. It's usefulness and profundity is vastly overstated though.