As a Lebanese, I find what you're saying both slightly offensive and slightly true. Lebanon, as a culture distinct from other middle easterners has existed for a very long time. Lebanon as an independent state has been invented in 1920, however there were multiple previous attempts historically to get independance.

We had high levels of autonomy under the Ottoman rule: https://en.wikipedia.org/wiki/Mount_Lebanon_Mutasarrifate

Some historical figures have reached levels of influence that would qualify as "independent lebanon" (if people were so good at administrative bookkeeping back in the 1600s): https://en.wikipedia.org/wiki/Fakhr_al-Din_II

The modern state of Lebanon fails in part because it's a "contrieved post colonial state", you're right. But claiming it has no historical foundations is misguided. It's wrong. Colonials hijacked a very legit idea, and turned it into a failed state. It's different.