This is a basic overview of Minecraft Live 2023.
Everything mentioned will be in Minecraft 1.21
Mob Vote Winner: Armadillo. (tbh I was shocked) Also, The Breeze was added, using wind to attack.
New Structure: Trial Chambers. (It has rooms that test your skill at different things)
New Blocks: Copper Bulbs (oxidation makes the light lower), Grates, Copper doors, Copper trapdoors, Crafter (auto-crafting possible with redstone), Trial Spawner (Once all mobs are defeated,you get a reward), possibly stone pillars?