I don't think that Ooba was exaggerating there. If she wanted to say that they were out of Jura's league, she could have just said something along the lines of "Their power cannot be compared to any normal being".
But the fact that the 4 Gods of Ishgar were stated to be non-humans and for Ooba to stress that Jura is the "Strongest Human Wizard Saint" implies that the 4 GoI aren't human.
They may look like human or take the form of a human, but that's no surprise because we've seen many non-humans in Fairy Tail who look like human beings.
Like the 9 demon gates of Tartaros (Mard Geer, Kyouka, Sayla). All of them are biologically demon, but look like any normal human being would.
Humans like the Spriggans and Gildartz are all way more powerful than the 4 GoI. So I don't think it was used as a hype tool.
The 4 GoI being non-humans actually makes a lot of sense because it would explain why they look so young, yet have achieved the title of the "Top 4 TWS/GoI" for such a long period of time.
For most humans, it would take until Makarov's age just to reach 5th ranked TWS, and even the 5th ranked wizard is far beneath the Top 4.
Plus, Warrod is around Precht's (Hades) age, which is like 101 years old. And Precht needed a heart to stay fit for his age.
Warrod doesn't and is the currently the last living member out of the 4 Fairy Tail Guild Founders.