All these items recall the whimsy that was common in the "Adventure" and "Action" Legion eras ... more so than now, anyway. I wish the new conception, as promising as it is, wasn't quite So Very Serious.
"Birdman" would have been a hoot to see in a one-shot, but too much of the "Land of the Giants" -- remember that cheesy TV series? -- wouldn't have worn well in the long run. We're humans, and those heroes-among-us have to (mostly) be humanoid-like-us to resonate. Including in size. Riffs on the theme, yes, but not changing the theme, if it's going to consistently sell.