I feel like you’re intentionally overthinking some of this.
You don't say?
Animals counted, plants didn’t. That bit with Ant Man suddenly hearing birds outside was meant to point that out. Because that’s how he figured out it worked. He heard more wildlife.
It was half of all life, including plant life. This was already confirmed:
https://screenrant.com/infinity-war-thanos-snap-animals-plants-killed/
As for people reappearing, you can wave to away with what Tony told Hulk to do “Everybody comes back safe.”
I can get behind this idea, but is this not just a monkey's paw at this point? What is
safe? If everyone is brought back as a large group to rural Canada, they're effectively brought back safely, but not very practically and not very safe for very long. I'm not expecting the movie to really explain this to me, but I would like a better answer than
IT JUST FUCKING WORKS, OKAY?
I'm also not expecting you or anyone else here to answer that, either.
Falcon became Captain America in the comics. Was he exactly the same? No? But he can still fight in his own way. The fact that it’s not just a “palette swap” is a good thing.
Like the guy above me just said, Birdman did not earn the title. Steve showed back up and was all, "Well, hey, you were my friend, so take this. Congrats, Cap'n."
He's also completely outclassed by every other Avenger. I can definitely agree that he has the
spirit of Captain America, but he lacks the raw power to perform the tasks he will need to in order to succeed. Steve Rogers is essentially dooming him to an early grave.
The military was not trained to fight mega beast aliens. The first thing they tried to do in Avengers is nuke New York. Ross would immediately be a dick and try to have Captain America arrested. They wouldn’t be able to shoot effectively with all those heroes all over the place, ect. Take your pick.
Those Wakandan mega beast alien trainings must have been
intense. It's definitely more believable that a bunch of Wakandans are shooting aliens with laser spears without sights than trained soldiers with M4s. Bucky was in the thick of it with an M249 going ham on them.
Earth was being invaded by that point, albeit on a shitty small scale. It would have been cool cinematically and also make sense to bring in actual soldiers to help. Hell, have them show up right next to Captain America as a call-back to the first Captain America movie. A company or platoon of soldiers isn't about ready to call in a tactical nuclear strike, my dude. The Davy Crockett got phased out in 1971.