IMHO, The Body Snatchers was a silly novel, but the 1956 film adaptation was entertaining. Not the best 50s SF movie, though. That is, not up to the level of Forbidden Planet (Anne Francis could induce nocturnal emissions ) or The Day the Earth Stood Still. However, all three films do carry the weltanschauung of the period. It's too bad that the studio forced director Don Siegel to change the ending. At least it was not bloated with special effects and lengthy chases, which turn most modern movies about simple stories into marathon sitting exercises. I keep telling my wife to skip the drink and just eat her popcorn.

Which reminds me. Apparently the first subliminal messages flashed on a movie screen were



and

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

I have to echo that Anime (if you don't mind watching Very detailed animated shows) have a LOT of these stories out there. I'll name a few:

Attack on Titan (Humanity has tightly packed themselves in a multi-walled city to fend off giant human like giants)

Robotech (The story was changed from the original Japanese but for the better IMO)

Sword Art Online (There is a sequel airing in Japan right now)

Those are just a few and I know there are lots more! If you watch any of them let me know.