It seems one mutation in the original virus perhaps led to the Covid-19 pandemic
It seems that there was one mutation in the genetic material of the virus, which enabled the virus to infect humans.
This mutation coded for an alanine, instead of a threonine (different amino acids). This change made it more
difficult for certain sugars to bind to the attachment spike protein which enables better attachment with the human receptor. Apparently, those sugars got in the way of the attachment.
It is likely, that this mutation has occurred many times and until the virus infected a human, it may not have been a trait that was selected as favorable.
As we have witnessed with the emergence of new variants, it seems that the virus readily mutates.
Those mutations that are advantageous to the spread of the virus are selected for.
While it is possible, that the bat directly came in contact with the human, it is more likely, that the bat bit an animal (perhaps a pet, livestock, or other animal that comes in contact with humans) and it was passed onto humans by such an intermediate animal, perhaps from a sneeze or cough from that animal.
You can read about this new research from the following link;