I think the graphics need to be improved and the armor for the animals too.

Graphics can be improved by adding 3D textures; For plants, you can make them completely 3D, creating pixelated plants that look like the real thing. And for the items in the inventory, make them also 3D, and some can even be given animation, for example, a burning torch, and of course, make the placed blocks also three-dimensional, add a 2nd layer as on the skin. I think it will be beautiful. You can also add voluminous leaves to the vine, which will make it more realistic and beautiful; You can also add protruding leaves to the foliage on the 2nd layer. You can also add particles of falling leaves.
It would also be nice if, when the player is on fire, the fire would be several times smaller, and the shield on the screen would be half the size. I think the game needs to add OptiFine features like objects that glow when you hold them in your hand so they glow, add shaders, and I think the maximum draw distance needs to be increased to at least 48 tiles.
It is also worth adding the opportunity to break horse armor and the ability to enchant it, the same should be done with dog armor, which will appear in the near future. And you definitely need to add to the on-screen indicator of the effect not only what kind of effect it is, but also the time, how much time is left until the end, and the level of the effect.
I am sure that all this will not interfere with the players, but on the contrary will improve Minecraft.