no we dont need a million categories

You need to find a creeper at the place you find diamond ores, and those diamond ores need to get exposed. In set seed, that could be possible, but it require many luck to have a creeper spawn there. In short, using creeper in this category is luck-based

No.

Minecraft speedruns are literally all about luck and rng. If you so happen to get a creeper to blow up a diamond for a no structures run i'd love to verify it.