A forgotten race, typewriters are hardy creatures armed with natural armor and who are quite masterful at the creation of well-formatted documents. A post-human world will need plenty of paperwork and bureaucracy, so who better to deliver it?
Those in the know already realize that plants like the Venus fly trap have moved on from chewing up unsuspecting insects. They are now big enough to devour automobiles. Their fierceness, lack of foresight and insatiable hunger for meat should serve them well in a brutal, post-apocalyptic environment.
Highly probable that they will be brought to life by ghosts or some magnetic/electric explosion. Their strength is certainly in their numbers. Also extremely helpful is their ability to subsist without food, water, gambling or alcohol.
An obvious candidate if only for their great pride. Losing out the dominion over the Earth sweepstakes, would be devastating. Expect the robots to go down shooting. They are highly adaptable, insanely focused and could easily fit into our clothes. The betting man’s choice.
These terrible creatures stomping around, harkening back to the days of the dinosaur would in a way be cyclical but is the most improbable situation. The effects of radiation are unpredictable and there are a lot more intelligent candidates out there. But these monsters would scare most small mammals. If the battle for a non-human Earth comes down to brute strength, then the edge goes to these abominations. Their skills include warfare, tearing apart cliffs and land navigation.