In the original Planet of the Apes movie, long before Charlton Heston's character, Taylor, has his big moment of realization at the base of the remains of the Statue of Liberty, he encounters a bunch of talking apes, and non-talking humans.
I suppose one could suspend their disbelief and suppose that Taylor found it reasonable to assume that some kind of convergent evolution explains the remarkably similar species.
But... there's no way one could reasonably propose that the English language, and particularly American English, could have just popped up somewhere else by chance. To call the coincidence staggering wouldn't even come close to conveying the effective impossibility of it.
Shouldn't Taylor have realized he was on Earth the first moment an ape said anything to him?
Obviously, the decision to depict the apes as speaking English was a decision based on factors to do with production, and accessibility for the audience.
But was any kind of explanation in or around the story offered to justify how Taylor just seemed to take English for granted?