> I'm not a biologist but I do find it strange that COVID-19 is so infectious in humans. How can a virus which supposedly 'naturally evolved' in a totally unrelated animal species (bats)

Bats are mammals, and so far from “totally unrelated” to humans, but...

> be so well adapted to spreading between humans?

So, Spanish flu wasn't of avian (far less related to humans than bats) origin but was also a man-made bioweapon?