People have speculated, it's a good guess. Q just hasn't confirmed any guesses
Mithra could even be a red herring. What if mithra has nothing to do with human sacrifice? I haven't seen any strong arguments that Mithra is a negative figure. That lion snake figure looks like the Gnostic demiurge to me. Tanit and Moloch seem to be sort of demonic entities associated with the transference of energies via sacrifice