I think this image on the Felidae wiki sums it up pretty well: https://en.wikipedia.org/wiki/Felidae#Phylogeny

Note that everything in this graph is extinct, except the 2 circled subfamilies at the bottom.

EDIT: I basically know nothing about biology and paleontology and am just an amateur wiki-binger, but it seems that the half-whale was further away philogenetically from any live mammals.

I’m guessing that the fact that this is not just some bones but a very well-preserved mummy is what makes this find special.