Not really much to go off of here. I feel like I recall some kind of upper class manor/hotel/castle at the start of the movie and some kind of change occurring. Maybe some kind of social revolution or people mutating. I recall an airship with some kind of scientists on board. I think the protagonist was a woman possibly looking for her son.
I say it’s like Fantastic Planet but it might not be fully animated. It could be something a long the lines of human actors with heavy amounts of CG or just very out there sets.
Solved: It was The Congress (2013). A bit harder to find because not all of the movie is animated. The change I mentioned was about 1/3 into the movie after the transition to animation.
Some lesser known movies that come to mind that match the animation style/era;
Delta Space Mission (1984)
The Last Unicorn (1982)
Marco Polo Jr Vs The Red Dragon (1972)
The Son of the Stars (1988)
Rock & Rule (1983)
Time Masters (1982)
American Pop (1981)
Gandahar (1987)
Starchaser: The Legend of Orin (1985)
Fire and Ice (1983)
The Point (1971)
Night on the Galactic Railroad (1985)
The Flight of Dragons (1984)
Wizards (1977)
The Thief and the Cobbler (1993)
Son of the White Mare (1981)
The Spine of Night (2021)
Nova Seed (2016)
A Cat in Paris (2010)
Memories (1995)
Little Nemo: Adventures in Slumberland (1989)
Hope you find what you’re looking for, please let us know if you do!
It was The Congress. I’ll have to take a look at some of the movies in your list though