So on what is it founded? I mean, we humans trust it (and depend on it for our own survival) A LOT.
Why??? What "validates" logic that we humans should trust it so?
What validates logic, the Principle of Contradiction, in our thought processes is merely a high probability of truth, belief, after extensive observations of fact. It's only a probability. Pure logic, Law of Contradiction, would deal with certitude, a different animal intuited without fact.
If logic isn't valid, then it is valid.
Sounds absurd? That's because logic rules out contradictions; but if you rule out logic itself, then contradictions are allowed.
Well, you may ask, what's the big deal about ruling out contradictions? Ah ... that's something that reality itself does, as all our experience demonstrates. Logic is nothing other than a rigorous method of thinking that is consistent with reality. And for many of us, reality is the ultimate test of all our thinking.
I know that opinions vary; but reality is what it is, and it doesn't care about our opinions.