For example, what should I call the animal that came before ape and human (each version of some object)?
You might be looking for the word progenitor. This word is commonly used to describe a species that gave rise to another. For instance, "Australopithecus is the progenitor of modern hominid species."
Biologists often speak of a "common ancestor" when referring to a species which no longer exists, but from which two or more other species have evolved.
tinyD makes a good point in the comments. "Most recent common ancestor" would be the most precise term.
a common ancestor
works for a number of similar 'commonality' situations, when the similarities are derived from the same source.