Well, we live in a free world. Anything is permissible. As for enjoyable?
That first claim is debatable, especially if by "we", you mean everyone on the planet. The second claim is certainly technically false, but I get what you are saying. The third sentence is more in line with what I am focusing on, and my position has been that different people can and do enjoy different versions/depictions/adaptations of stories, depending on their individual sensibilities. One person can enjoy and/or prefer a depiction of a fictional character which is different from the original or most common depiction. Another person might prefer strict as possible adherence to the original, or even what they personally imagined to be the original. Neither preference is necessarily "correct" in an objective sense. However, we all naturally like to think of our own view as being the correct one, so we will sometimes skew towards describing differing versions in unfavorable and/or devaluing terms.
If one is adapting a particular story to the screen, fans of that story probably are one's target audience.
I don't think that is always the case.
Black Panther was a pretty good recent example of this. Anecdotally, most of the people I knew who went to see the movie had never heard of the character before he was introduced in the MCU. I will admit that I haven't researched it, but I'd wager that most of the people who saw the movie were not already faithful, versed "fans" of the comic book character and had probably never laid eyes on a Black Panther comic book.
Them being fans, it is safe to bet they like that story already as is. That's what they expect to see. Chances of them appreciating changes are there... but they aren't good.
Meh, again, I think you are projecting
your own personal individual preferences onto the public at large. I agree that
some people will view things that way, but not all, or necessarily even most. For example, I would consider myself a Superman fan. I
loved the Christopher Reeve version of Superman. I grew up with it, had it on VHS, and watched it literally hundreds of times.
Man of Steel made tons of changes, to iconic stuff, the story details, the music, the characters, including Superman himself. I was perfectly fine with all of it. I loved
Man of Steel. I thought it was a fantastic update. Some people didn't like it. I'm sure there are folks who grew up with George Reeves as their version of Superman didn't care for the Christopher Reeve version. People have differing sensibilities. My point again, is that especially when it comes to made up, fictional stuff, it really boils down to individual personal preference, rather than objective "correctness".