Every long running series that is considered to have "good" lore has gone under countless revisions.

Lore constantly updates itself to make the universe more dynamic, and fun to experience. Indeed, only games with bad lore remain the same, as they refuse to accept that some decisions in past games were terribly dull, or simply just crap.

Much like the change of Cyrodiil from a tropical jungle with no cities beyond the Imperial city, which was a fairly dumb idea in the long run, to what we got in Oblivion, things change constantly to make more sense, or offer more dynamic gameplay.

The change of ghouls was done to make the different types more distinct, and offer new gameplay options for each.

These changes, no matter how much they happen, do not make any past game non-canon, as the main story and side quests still remain, all it does is change completely pointless visual appearances, which change every game anyways, and changes how things are dont mechanically in each game, which changes every game anyways also.

And this isn't even taking into account that people like Tim Cain and Chris A, the people who made the old games, do feel like it fits lore. So obviously they do feel like ghouls were always this way, despite what may have been shown in the game itself at the time.

I don't recall that cyrodil had no other cities beside the imperial city, in fact I'm pretty sure it had more cities before it was retconned, like sutch for example was a city before oblivion came out, and was only an abandoned fort afterwards.

And it being changed from a tropical jungle to a standard forest within the span of 6 years only felt like a cop out to me (as Npcs in morrowind still referred to it as a tropical jungle ).
I personally would have liked the dense jungle over the forest setting, but I'm 99% sure it was changed due to technological limitations at the time, not to make richer lore, which is understandable, but I never saw it as adding to the lore or making it better.

In Arena there was only one city in Cyrodiil. The Imperial City.

Only Arena had the single city Cyrodiil all games after that didn't

Yeah but in daggerfall and morrowind cyrodil had way more cities, in fact the entire world had been retconned since arena because it was just a generic fantasy game when it was just arena.
And just because you could only go to one city in the capital didn't mean there was only one, there was only one that had relevance for the story.

Read the pocket guide to the empire from morrowind, there was way more than one city in cyrodil.

Cyrodiil wasn't in Daggerfall and there was no mention of its cities besides the IC. And relevance to the story has nothing to do with the cities in Arena. Arena had tons of cities. I'm pretty sure that in most areas they had more cities than in modern TES lore(Vvardenfell and Iliac Bay being the exceptions). Look at Skyrim for example.

And don't get me started on Morrowind. That game retconned lore like no other. You can't honestly bring Morrowind up in an argument against retconning. It takes away all your credibility.

Start a new thread, please. This one is at the limit.