From where though? Not everyone from all the cultures celebrated the same holidays, the English would have different celebrations from Germans, Dutch, Scots, etc. And then it would heavily depend on your religious traditions: Presbyterians wouldn't celebrate Christmas or any kind of holiday like that, Anglicans might have some saints' days (St. George's Day).

So a few that would be generally celebrated across the colonies would be days of historical or national importance. One being the King's Birthday on June 4, even in 1775. Basically July 4 for loyal subjects in America -likely one of the biggest events for the year. Big feasts and toasts to the King, lots of huzza and general revelry. Another would be Guy Fawkes Day, or Pope Day with burning an effigy of Guy Fawkes who planned on blowing up Parliament and the King, and was essentially an anti-Catholic holiday. May 1st was May Day, something derived some Beltane traditions.

New Years Eve had much the same sentiments we do now, but was probably a bigger celebration than Christmas at the time. For Scots it would have been their hogmannay, but the rest celebrated a similar good tidings and cheer, bringing gifts to neighbors.

The Irish had their St. Patrick's Day but it wasn't a national thing like now. It was mainly relegated to Irish Societies or clubs within cities like Boston, or if there were enough Irish troops in a city or fort to make a parade. Scots would typically celebrate St. Andrew's day much the same. These weren't big spectacles though, they were mainly feast days.

A lot of the holidays Americans today have some origin in colonial days but they're much transformed than what they would have been at the time. A lot of the colonial holidays went away because after the war when Americans broke ties, there was a push to even culturally separate from the British (I'll argue it was a bit choosy though).

I am looking forward to sharing this with my kids! Thank you for the nuance and details!