There's a certain species of Greek narrative where the unclear circumstances in which a person has disappeared--or, e.g., that their bones cannot be located--is taken to suggest their deification. There's another species where the person has clearly died, but is then resuscitated/resurrected and immortalized. For example, the early Christian patriarch Theophilus answers Gentile skepticism of the resurrection of Jesus (and resurrection in general) by countering "you believe that Heracles, who burned himself, lives, and that Asclepius, who was struck with lightning, was raised; and [yet] you disbelieve the things that are told you by God?"

The scholar Dag Øistein Endsjø has done a lot of good work in this area recently.

It's unclear how historical some of the details in the New Testament gospels about this are are. Some scholars question if the historical Jesus was even buried/entombed at all. Others might accept that he was, but that perhaps the body went missing. Either way, if the body somehow could not be located, this might prime speculation about his possible deification.

Also, it seems that the very important followers of Jesus had visionary experiences in which they "encountered" Jesus. This would only further those speculations about his immortalization.