Your examples are created by stating situations in very broad terms that automatically downplay the differences. If you want to see that level of comparison as proof of similarity, that's up to you. But playing that same game, one can find comparisons between all sorts of things, including just about any epic science fiction or fantasy epic ever written. It's the whole Texas sharpshooter situation that produces things like that list of coincidental similarities between Lincoln and Kennedy. I can't say, for example, that I ever saw Sheridan as a Gandalf figure nor was the King in LotR a time traveller but if those comparisons work for you, go for it.
Every post I ever saw by JMS on the Babylon 5 newsgroup had him denying that he was emulating this work or that and, trust me, fans claimed he was borrowing/stealing from everything. Did he borrow elements here and there? I'm sure he did, either consciously or subconsciously. But there are only so many ways to write an epic and there are bound to be comparisons between any two epics. If that weren't true, there wouldn't be "master plot" books out there with formulas for different types of stories. A big reason why I don't try to find the similarities is that it annoys the heck out of authors to constantly be told that they stole everything from some other story. It annoyed Tolkien. From what I've seen of his response, it annoys JMS, too.
But at the very least, you've got to admit that two characters in two different epic good versus evil dramas dying by falling into a bottomless pit, one named Kazak'dum and the other named Z'ha'dum is a little more than a coincidence.