Turmeric can go both ways, but the ground turmeric that's historically common for preservation reasons is much less flavorful than the fresh root. It's mostly a color thing.
Of course, we can also just open up a medieval cookbook to see what they say. The Forme of Cury is a nice 14th century example that's available from Gutenberg: https://www.gutenberg.org/ebooks/8102
As to colours, which perhaps would chiefly take place in suttleties, blood boiled and fried was used for dying black. saffron for yellow, and sanders for red. Alkenet is also used for colouring, and mulberries; amydon makes white; and turnesole [for yellow]
Alkanet is commonly used today for Rogan josh, but historically would have been more known for rouge and dying wine. A Mediterranean cookbook might have instead chosen amaranth for the same purposeHave you ever cooked? Most stews use spices for colouring. A paella looks ill without saffron in it.
There are legendary varieties that are lost to time. Occasionally we rediscover them, and we get to compare. Usually the modern industrial varieties are pale imitations.
warabi-mochi, nata-de-coco, aiyu jelly, kokum, annindofu, kanten, blancmange, to name just a few
If anything I'd say my take is less insulting to these other dishes than you are by comparing them to jell-o
You have really good eyes. I can't tell the difference
Pandan Jelly
https://asianinspirations.com.au/wp-content/uploads/2018/12/...
Lime Jell-o
https://centslessdeals.com/wp-content/uploads/2022/02/Lime-J...
Lemon Jell-o
https://www.shekeepsalovelyhome.com/wp-content/uploads/2019/...
Aiyu-Jelly
https://www.shutterstock.com/image-photo/aiyu-jelly-46238794...
Raspberry Blancmange
https://themoderngelatina.com/wp-content/uploads/2010/09/img...
Strawberry Jell-o
https://thefoodcharlatan.com/wp-content/uploads/2014/04/IMG_...
https://www.youtube.com/watch?v=Cvvshpw4FxM
Check at 6 minutes into the video.
edit: it looks like that vid had some steelhead (trout) mixed in? This is more like what I have seen, but the color is even more "dulled" in person https://www.youtube.com/watch?v=e09UmeqAd4g