That’s an excellent condensation of what’s sometimes called the “common-sense agnostic” or existential realist position. You’re tracing a few deep threads that have occupied philosophy for millennia: epistemic humility, the limits of revelation, and the thin ground of reason. Here’s how your note can be unpacked and refined without losing its clarity:

1. Epistemic Humility You start with the unavoidable fact:

“Nobody knows why we’re here.”

This sets a posture of epistemic humility — the recognition that no human (or institution) can claim absolute knowledge of existence’s purpose. Even if a revelation were received, one could never confirm it externally. Philosophers from Sextus Empiricus to Kierkegaard to Wittgenstein have landed in this uncertainty: truth might exist, but our capacity to know or prove it is limited by our position inside the system we’re trying to explain.

2. Limits of Revelation and Reason You capture two major boundaries of human knowing:

Revelation: unverifiable by outsiders, indistinguishable from imagination.

Reason: internally coherent but system-bound — the rules of logic themselves arise from within the same reality they attempt to explain.

That last idea echoes Gödel’s incompleteness theorem and Kant’s critique of pure reason: any rational system sufficient to describe the world cannot account for the source of its own axioms.

3. Religious Fragmentation Your observation that even within Christianity there are contradictions and moral failures is the empirical proof of your premise. If revelation were perfectly clear, divisions would not persist for centuries. So the diversity of sects becomes evidence of interpretation’s frailty — humans projecting limited understanding onto infinite claims.

4. The Tragic Loop

“We’re doomed never to know the truth even if we know the truth.”

That paradox is beautifully put. Even if someone glimpsed ultimate truth, memory, language, and ego would distort it upon expression. This is the fallibility of transmission — reminiscent of mystic traditions (Zen’s “finger pointing at the moon”) and Nietzsche’s insight that “truths are illusions which we have forgotten are illusions.”

5. The Minimal Common Ground You close with what might be the foundations of a secular existential ethic:

We are alive.

We can choose our attitude.

Explanations come only from reason and observation.

That’s the minimal floor of meaning — the shared, testable, experiential domain. It’s a kind of Stoic-existential fusion: accept uncertainty, but act with integrity and awareness within it.

If you wanted to expand this into a short essay or philosophical manifesto (say, “The Common Sense Perspective”), we could structure it around:

The Problem of Knowledge – why certainty is impossible.

The Collapse of Authority – religion, ideology, and reason’s limits.

The Human Condition – fragile but conscious.

The Common Ground – attitude, reason, observation.

The Way Forward – living meaningfully without knowing why.

Would you like me to turn this into that short, polished essay form next?