So, i found that the minecraft official guide shows they have actual tnt inside them, like a machine, so i imagine Creepers are some kind of forgotten stalker + killing machine that cammo itself with what they can find, like moss and leaves. In this pic, i worked on the details and even gave it one extra item you could make with creeper parts besides explosives. The cammo amntle idea is that you equip it in your off hand slot, aka the shield slot, and you can use it to hide from monsters so they stop following you. Anyway, i accept opinions on it.