Truth is what can reasonably be proven using the scientific method. There are truths we have not proven, do know about but until they are discovered and proven they unknowns or suppositions or opinions.

its relative

Unless in a state of unity, there is conflict which means two positions. Therefore the one cannot acknowledge the 'truth' of the other and if a state of unity exists there is no polar position i.e. no 'it' and 'not it' so all questions no longer exist. Even self awareness is non-existance. Therefore, no 'Truth' can exist.

A lie!

Universal 'truth' is similar to universal 'love'. Beauty is in the eyes of the beholder?

Truth (that which is in accordance with fact or reality) would by definition be universal in the sense that we all exist in the same reality and face the same set of facts.

It would never be universally assented to, though, because not everyone's perception and understanding of reality and facts are the same.

The more people understand and are committed to critical thinking, the more their perception and understanding of reality and facts will converge.

Nope. Most of the time, most people wouldn't know the "truth" if it bit them in the ass.
Why else would so many still believe in gods and religion?
There is NO truth to any of that bullshit.