I'm not saying though, that this is a criteria for calling any machine a computer. But it's probably what sets Zuse's achievement apart.
UPDATE: I've just learned that Babbage's language was also Turing complete. So Zuse's achievement is solely having physically built the first working computer, while Babbage's machine was never realized.
Leonardo da Vinci also invented tanks and helicopters, and then it took a couple of hundred years to build some.
Or more seriously put: It's a concept for a machine with 55k moving parts and powered by a steam engine. "Would work" is probably a bold statement considering how far off theoretical designs always are from the engineering reality, by all experience.
http://blog.plan28.org/2016/05/spring-2016-report-to-compute...
If you read further, it becomes pretty clear that it's more or less a theoretical idea. A great one though, granted.
That's debatable. Maybe it was turing complete on the paper but it was never designed to be and it was not used as a turing complete machine.
And the fact that Z3 was based on binary, while the analytical engine wasn't.