Here I decided to do a poll with as much films I’ve found that generally aren’t adaptations to like a ‘source material’. I did arrange these based on the times they were released.
I’m open for discussion for incase I missed any, you could feel free to point that out to me to add any more in the poll Though I will not allow people to add news answers themselves in case they unknowingly put adaptations.
Though Lion King did have inspirations from Hamlet and Bambi(which is loosely based on a German book, “Bambi a Life In The Woods”).
Also, I’m unsure if whether or not Frozen counts as an adaptation cause originally Disney planned an adaptation of The Snow Queen, but had changes going on.
There’s The Emperor’s New Groove which despite the phrasing of the title is said to to bear no relation to this classic Danish fairytale The Emperor’s New Clothes although it’s said that coincidently both stories involve an emperor being tricked, so I don’t know if I should leave that out.

Also Zootopia and Moana.

Frozen counts as Disney's re-do of Andersen's The Snow Queen. Frozen was an idea left over from the very early days of Disney. Walt Disney just didn't get to do it in his lifetime. Now, I wish he had.

But out of this list, my faves are Atlantis, Lilo and Stitch, and Zootopia.

Zootopia and Lilo & Stitch.

UPDATE: I now decided to include The Emperor’s New Groove(which took place between Dinosaur and Atlantis) since it’s said that the film still didn’t actually have a relation to The Emperor’s New clothes from what I’ve searched.
Also, I kinda forgot to have Atlantis as “Atlantis: The Lost Empire” oh well. :P

Wait! I’m also thinking about one more film, A Goofy Movie. Well, in one site where people were having a forum based discussion on which animated Disney film aren’t adaptations. None of them ever mentioned that film and it even got a theatrical release, though it did follow up this Goofy tv series from what I heard. Likely another update to consider.
EDIT: I now decided put A Goofy Movie given that it did have a theatrical release even after being a follow up to the Goof Troop tv series. Let alone Goofy was just made by Disney next to Mickey Mouse and Donald Duck.

I also fave Fantasia(would’ve been interesting if it did bomb in its first release due to World War 2 then there would’ve been those updates Walt had originally considered. Maybe it could’ve be a Disney tradition had that happened) and Wreck-It Ralph.
I do like the others as well except Home On The Range.