TNT bc in 0.30 there is TNT and no creeper ( Except for Pixel Art)

(SERIOUS COMMENT)

TNT came first. If you look back at the early Alpha days, you would spawn with TNT in your inventory. At the time, there were no mobs and no life bar. So TNT came first.

the creeper because u cant get tnt without the gunpowder from the creeper so it would be rather hard for you too get tnt from anything else that i know of in my time in minecraft

first the miners found sulfur underground, then they made gunpowder to make TNT out of it, but there was some left over so notch suggested they throw it into some hole and forget about it, the gunpowder reached a small whole in the void and the particles mixed and created a new being, the creeper :3......... or maybe the creeper just came first xD