Talking about giant beetles and how I used them: pack animals for the underworld, war elephants for goblins and the like, or car sized monsters in dungeon corridors

Talking about giant bees, giant wasps, and how I used them: like Aliens in a hive, and as mounts for lizard people

Talking about bears, laser eyes, and summoning angry flying bears

Talking about the basilisk (also known as the cockatrice)

Talking about giant apes

Talking about a simple 2d6 system I use for online gaming. One opposed roll to determine initiative, to hit, and damage.

On the things I do for prep: random tables, monster lairs, jotting down some shallow ideas, run with it in such a way that I don't need to improvise in depth but that shallow encounters point to other shallow encounters, take note of what happens at the table and let that inspire more ideas that build on the previous ones. Last session's shallow idea thus turns into the seed for the next session's good idea.

The gods, the realms, confusing and overlapping portfolios, how even the evil ones need to provide a benefit.

Things to consider when writing RPG text: keeping it short, keeping stats short, keeping it all in one place, don't require leafing around, have art that referees can show to player, have maps that referees can annotate

The mini settings I like to generate where the environment or the map generates inspiration for conflict: the river valleys generate political entities, the swamps and mountain peaks religious entities, add secret societies, a long war somewhere else...