No, I don’t see halflings as a gnome relative, and I don’t see why they would need to be either, leopards, housecats and bobcats all exist but you don’t see people going oh bobcats are too similar they must of course be crossbred housecat-leopards,
The halfling and the human are both there for the audience to relate to but in different ways, humans are human, so of course we’re going to relate to them, but they’re books and movies fantasy humans, they fit into the heroic tone of the world with some random human farmer to pick up a blade grab a horse from the fields and gallantly ride to the horizon to slay the dragon that’s terrorising their village and you expect them to succeed, but halflings, halflings we’re meant to relate to on a different level, on a societal level, with their cozy homes and nice meals who are far removed from the dangers of the world for the most part, if we were sent to the fantasy world while we’d resemble humans physically our attitudes would be more comparable to the halflings.