Is there such a thing as truth? Can humans comprehend it? What is true? What kind of thing is truth... etc.
For these to be meaningful questions requires metaphysical principles (either explicit or implicitly).
Is there such a thing as truth and can humans comprehend it?
Yes and yes - because it is not coherent to deny truth nor to deny that humans can comprehend it.
To deny truth or say that humans cannot comprehend truth is simply to claim as a human that you know that it is the truth that there is no truth or that humans cannot comprehend it.
So we must assume that there is truth and humans can discover it.
The only alternative is non-cognition.
This is not a discovery, it is not a consequence of experience, nor science, nor of any kind of investigation...
It is a simply rational necessity that humans acknowledge the reality of truth and its accessibility to humans.
Everybody is born knowing this stuff, everybody in the world and throughout history does in fact know it and live by it.
(Everybody in the world and though history, that is, except a statistically insignificant minority of clever silly intellectuals who have exchanged this obvious metaphysical basis for nihilistic, self-refuting and self-destroying psychoticism. I mean people just like myself and nearly all of the readers of this blog - for at least some period of our lives - and the entire ruling elite of the West.)
OK - that is sorted out (really, it is sorted out - no need to dwell further on it).
Next thing is on that basis we can investigate the nature of truth (e.g. that it must be eternal and universal), how humans in fact get to know the truth, limitations on knowing the truth - and stuff like that.
But such investigations are underpinned by the absolute metaphysical assurance that in principle there is a truth to be known and we can know it.