We'd have to see new Beastmen in theory to have Shiva around. As it stands, there's only Titan, Ifrit, Ramuh, Garuda, and Leviathan's beast tribes actively mentioned in lore. The primals can only be summoned by beastmen, so, we'd have to have said race around to perform the ritual.

The Kobolds worship Titan. (As obvious by their flag, culture, and if you do some digging there's 100% proof in the .DATs)

The Amalj'aa of course worship Ifrit, as we all know.

It is easy to assume the Ixal worship Garuda, as they are bird-like and use aero-based abilities.

The Sylph are quite magically-inclined, and their flag has a lightning bolt on it if I am not mistaken. I think they even drop lightning clusters. Ramuh is probably their primal.

The Sahagin and Leviathan are self explanatory.

...Now Shiva is a tricky one, but I have a theory on that. There's a quest out there that mentions there is a group of blacksmiths that work under the banner of "The Gigas Forge". It could have been named after the Gigas, which in FFXI had incredible strength - a powerful trait for a blacksmith.

It's very well possible that the Gigas are the beastmen tribe of the northern regions, and they worship Shiva.