Fun history lesson, Cinco de Mayo was first celebrated in the Mexican communities of California. It celebrates the Mexican victory over the French at the Battle of Puebla in 1862. It was widely popularized by the Chicano movement in the 1950s.

Battle of Puebla Day was and sort of still is a holiday in Mexico, but it's not on any official observances list, but school children do get the day off nationwide, and there's reenactments and parades in Puebla. Widespread celebration fell off after the dictator who was fond of the holiday was deposed in 1911.

More fun history, the French won the Second Battle of Puebla a year later and then occupied Mexico City in their attempt to found a new Empire out of Mexico, because Napoleon the 3rd wanted one, but was way too incompetent to war with the rest of Europe. (He did some fighting in the Crimean War, but forgot to bring the artillery, the first Napoleon was an Artillery commander)

And St Patrick's Day is more of an America and Ireland thing. It's certainly not British.

I learned about that (in detail) from a Youtube channel about booze, of all places. It was surprisingly interesting!

Wow you ain’t kiddin. https://zoa.org/events/parade/

That makes sense, and I agree. I even mentioned the differences in my comment.

I just feel like phrasing it a little better makes for more solid logic so that it's not as easy to refute or dismiss as is

No it’s true based on a comment above this appears to NOT commemorate any particular historical event but just a thing. https://zoa.org/events/parade/

I never said otherwise. If you just argue on it on those grounds instead of claiming the US doesn't celebrate any other foreign holiday then I think you'll have pretty solid logic.