(((They))) would engineer multiple versions to overwhelm, the world; saying it was left to bats first makes me think someone would instead expose it to bats so that the virus has to adapt to their bodies–high iron–thus transferring a certain potency the virus would have for, say, someone who drinks lots of baby blood? High iron–high (Cov)FeFe.
Vague reference for why bats would make a great dynamic host for subverting the virus to instead attack certain "groups" or "peoples" comes from…
https://arstechnica.com/science/2018/03/suck-on-this-the-genetics-behind-vampire-bats/
> It has almost no carbs, fats, or vitamins; its high iron levels can disrupt heart, liver, and pancreas function; its obscenely high protein and salt levels can cause renal disease if nitrogenous waste products build up. It contains pathogens. It clots.
Basic composition analysis, but maybe someone could back it up further.