A bunch of reasons, really, and check out this previous answer to [I live in New York, which is between New England and New Jersey. My girlfriend lives in New Hampshire, has family in New Brunswick, and works in New London. When and how did the practice of naming places in the New World “New + a place in the Old World” begin?] (https://www.reddit.com/r/AskHistorians/comments/ilvvfn/i_live_in_new_york_which_is_between_new_england/).

In short: The Spanish started it in 1521 with Nueva Espana (New Spain) unless Amerigo Vespucci counts as starting it in 1503 with Mundus Novus, which means New World. The French came along in 1529 with Gallia Nova, or New France. And little ol' New England showed up long past fashionably late in 1616 in a book published by John Smith. My post details some other common "New" name sources as well as why they were named that. I'll also add part of Smith's reasoning was to make the foreign land more attractive and familiar sounding to folks back in England.

Also, these weren't the first places called New [blank]. These were the first New World European colonies named New [blank].