When a person passes away, it can be difficult to accept that they're really gone. This is a big part of the reason that almost any religion to have ever existed has some kind of concept of an afterlife. In Western society, the idea that somebody could be reborn as someone different is still at the less accepted end of the spectrum, but that hasn't stopped the internet from using the concept for an absurd meme. For the past couple of months, memers everywhere have been welcoming back significant figures of the past as today's celebrities.
There is no rhyme or reason as to which famous people are designated as reincarnations of the well-known deceased, but that's all part of the joke. Or is it? It's not like any of us have definitive answers for the mystery of the universe. For all we know, there could be some truth to these absurd proclamations.