You absolutely can infer their lives and their epochs. You cannot infer their evolution, only their existence.
But their epochs of existence have an elaborate structure, a succession of forms, and this pattern of succession constitutes ipso facto evolution. This is what Gould and others have referred to as the "fact of evolution". Of course, the theory that this succession is accounted for by "descent with variation and selection" does remain a theory, even if a well supported theory.
Do you mean to suggest that all the transitions in this elaborate structure of succession of forms were accomplished by some kind of extra-natural intervention? Somehow I don't think that is what "Intelligent Design" is aiming at.