Could anyone tell me whether there is any reliable evidence of a giant species of homo sapiens (or even Neanderthal) ever living on earth.
Well there is of course evidence of Neanderthals living on earth. But we can look at their skeletons and they were short and chunky compared to us: the average Neanderthal height was around 5'5''. So they were not giants. If that made someone a giant, then I would like to boast about how I tower above you mere mortals with my magnificent 5'7''. Behold me and despair! ... oh, wait, I'm kinda short.
Creationists like to put up Neanderthals as evidence of how it says in the Bible that "there were giants in the earth in those days" but this is because creationists are too fucking stupid to look it up and find out how tall Neanderthals were. And it's not like a secret, they could look it up. Neanderthals were in fact shorter than the average modern human, as creationists could have found out it they weren't too busy drooling out halfwitted lies.
And then you ask, is there any other evidence of giant humans living on earth? I shouldn't even have to answer that, Gregory, because you know. You know that if we had found giant human skeletons in the fossil record, then you would know about it because of all the giant human skeletons that we would have.
(There is the occasional freakish person who is eight or nine feet tall, but we know of no species with that genetic or developmental abnormality.)