And the beginning of his kingdom was Babel and Erech, and Accad, and Calneh, in the land of Shinar. Out of that land he went forth to Assyria, and built Nineveh and the city Rehoboth, and Calah, and Resen between Nineveh and Calah; the same is a great city.In which case it does indeed seem to say Nimrod founded Nineveh. The Geneva Bible seems to agree with this reading, so it's not just something modern translators came up with. Nineveh is old enough to go back to the time of Enmerkar, it's Wikipedia page says it's first time of prominence was about 2900-2600 BC.
That does provide justification for identifying Ninus of Greek sources with Nimrod. Problem is those Greek legends are still clearly highly corrupted and removed from the original story.
Ninus could derive from the Sumerian prefix(s) Nin or Nun. It has been claimed that the deified form of Nimrod was Ninurta, a war and agriculture god who has been called a hunter. Ninurta's daughter Ninsun was the mother of Bilgames which would justify making Gilgamos the grandson of Enmerkar as one Greek writer said.
Nineveh seems to be the only of the four Assyrian cities founded here that is still known by that name (and Moses may have only used the name he knew it by, not it's original one). Nimrud however is a very modern name for that site, first applied to it in 1760 AD. Nimrud was in antiquity called Kalhu, so it's clearly Calah. Rehoboth-Ir is almost identical to the Hebrew phrase "rehovot ir", meaning "streets of the town" or "public square of the town", so it may not refer to a separate city at all but simply to Nineveh. Verse 12 not mentioning it again but only Nineveh and Calah would further support that. Resen hasn't been firmly identified, but Karemlash is a popular theory. I personally don't think Asshur is one of the cities mentioned here, I think Asshur was founded by Asshur.
My point that we don't really know the moral character of Nimrod remains, that especially means those who think Nimrod is The Antichrist need to accept they've built their arguments on a shaky foundation. And that not every pagan heroic figure is code for Nimrod. And Nimrod being deified by others later doesn't mean he himself approved of it.
On the subject of Semiramis. Even if there was a wife or consort of Nimrod that inspired some of those Greek stories, that wasn't her name, that name comes from the 9th century BC Assyrian queen. If the historical Nimrod was Enmerkar, then we should be looking for her in those legends. But since The Bible doesn't mention a lover or offspring for Nimrod, (at least not identifying any person as such), we should never forget we're leaving The Bible when making such speculations.
Even the apocryphal texts like Jasher don't add an important consort for Nimrod to the mix. "Jasher" makes Nimrod the same as Amraphel which is just stupid.
In the Enmerkar poems, which were written down generations after they take place, the conflict between Enmerkar and the Lord of Arrata seems to revolve around the goddess Inanna. She seems to have been with the Lord of Aratta first but now has a fondness for Enmerkar. While she at times seems annoyed by both kings acting like they can own her, she ultimately favors Enmerkar. If she wasn't explicitly identified as a goddess, it would sound a lot like a love triangle. In fact both kings do seek to refer to themselves as her true Bridegroom.
Maybe that's what it was, but the story became altered in the passing down as Inanna was deified. Maybe the origin of the custom of the Ritual Marriage between the King of Uruk and Inanna via her High Priestess was that Inanna originally was the wife of the first king of Uruk.
It's possible that this process broke her role in the story into separate parts, both the goddess and mortal women in the stories who seem to function as agents of the goddess. Mainly the "old woman" who defeats Aratta's magician and later marries Enmerkar. Who some interpreters of the poems (ones who take them at face value not looking for a real history behind them) interpret wasn't literally old but being described as such for some mystical reason.
In the Greek historiography Semiramis is given a divine parentage but then is said to be raised by the shepherd Simmas. I can't help but suspect Simmas could come from Shem. And it also claims she was married to someone before Ninus but who that was I doubt the Greek sources got right. Armenian legends claimed Semiramis married an Armenian king Aras after Ninus died, it might be out of patriotism that the Armenians switched the progression of her love life.
The important thing to remember here is just because the pagans told pagan stories about them doesn't mean they themselves were pagan.