No, it isn't, but this would make the PC (not the class, mind you) that creature type. Just like Elves are now considered both humanoid and fey, a draconic bloodline sorcerer would be dragon and humanoid (and possibly more, like fey if the sorcerer is an Elf).
Every sorcerer subclass could easily be tied to one of the numerous creature type...
From PHB, XGtE, TCoE:
Draconic Bloodline - Dragons
Wild Magic - Fey (or Monstrosities)
Divine Soul - Celestials
Shadow Magic - Undead
Storm Sorcery - Elementals
Abberant Mind - Aberrations
Clockwork Soul - Constructs
Also, if you use them:
Lunar Sorcery - Beasts (or Fey)
Pyromancy - Fiends
And that still leaves a few creature types not even used yet, which work if you want to add some UA origins, like obviously Giant Soul - Giants.