The Before Dimension: A Treacherous Post-End Primeval and Lush Wilderness

Why add the Before Dimension? 

It has now been over 15 years since the last dimension was added to Minecraft. We already have "The End," so why not add "The Before," like a prequel to Minecraft's story? I want to see the past world Mojang envisioned the Sniffer lived in! This can also be a space to add biomes, mobs, structures, and even weather too wild or dangerous for the Overworld, like acid rain, floods, earthquakes, and meteor storms.

The Before

Use a Time Portal to travel to the Before (same size as End). While the End is horizontal, The Before is vertical and aboveground. The Before has a roof made of leaves supported by immense trees. The ground is made of spongey reddish Peat and Moss. Pools cascade to the ground with massive falls around lush karsts. Structures have a Caveman or Steampunk aesthetic, and the Time mechanic is featured here in contrast with the End's "space."

Sniffers and prehistoric mobs (Sabertooths, etc.), also allowing Minecraft to add hostile (but extinct) animals. Maybe smaller dragons too?

Possible Before Biomes: 

The Sporest: A dangerous fungi forest that gives off sleep-inducing spores.

The Burble: A jungle-like wetland made of deadly bubbling goop. 

The Quickmire: The lowest biome, a desert with rippling dunes and quicksand.

The Tar Pits: A desolate biome filled with bones and burning tar, and petrified trees.

The Craterland: A craggy place dominated by craters and meteor fragments.

The Canopy: The uppermost biome of the Before in the giant leaves.