I had a really neat idea about playing a changeling bladesinger who most likely pretended to be elven to learn the art, although I did have a not-quite-RAW idea about the old switched-at-birth changeling myth, where his elven "parents" would have taught him before he slipped up and they realized what he was.

He was actually three characters in one: a mostly nondescript human "bard", spinning extremely tall tales about a mysterious elven bladesinger who doled out vigilante justice at night (also the changeling), and the changeling himself, who hated the way people looked at his true form, would only have revealed it to the party if he had no other choice, and really just wanted to be a hero in a group of adventurers, doing the kind of stuff he made up and sang about in taverns.

I came up with this concept a few years ago, but even before COVID I was kind of my group's forever DM, so even if I ended up at a gaming table again soon I probably wouldn't get to play it, so if you like it, feel free to use it. You cannot steal what is gifted!