Serious:

So the cover seems to depict a human riding a deer. There is also the subtitle: "Survivors." Plural. But we only see the deer and the human. No civilization or technology or even ruins is shown; it's just forest. So my guess is that the titular "survivors" are the deer and the human. The story starts with the human waking up in a cave with no recollection of how he got there or even who he is. Needing things like sustinence and information he sets off only to find forest. When almost eaten by a bear he is saved by a deer and turns out he can telepathically speak to the deer. There is a deer prophecy about the coming of their King and the human slowly starts fulfilling the prophecy even though he's doing little more than just trying to survive.

Not Serious:

Kuzco Buckington Winthrope III is the crown prince of the kingdom of Clopinhagen. On the day he is to be crowned king, the witch consort attempts to poison him but her bumbling assistance mixes up the poison specifically for Kuzco with essence of deer, turning Kuzco into a deer. He then ends up accidentally on the cart of a traveling merchant leaving the city... until the merchant finds a talking deer in his cart. We laugh, we cry, wrong levers are pulled and after the roller coaster ride the deer is finally reinstated as King but is still a deer.

From my knowledge of LNs… The majority are: Isekais, in less technically advance eras, involve lots of cooking, the MC is OP and there a school somewhere.

Theory -

The MC is a deer, he was one of santas reindeer but after being hit by truck-kun he is reincarnated to another world as an OP deer. He starts with max stats with the skill limit breaker to allow him to transcend the gods. The world is in the pre historic era and after attending the most prestigious school (at which he was bullied) he and his human friends set of to save the world from the demon Lord. They travel while eating dinosaur meat (which spans 10 pages each time they eat) until he one punches the demon Lord so hard the demon Lord gets reincarnated into the MCs original world. At which point he is crowned the deer king!

Ashitaka after the film, leaves human society and Yakul becomes a deer king, then they travel the land. (Princess Mononoke Alternative Universe)