Phylogenetic network analysis of SARS-CoV-2 genomes

[vi-va]

That makes the similarity between bat coronavirus and type A insignificant in comparison to the similarity between bat coronavirus and type B, C.

you seems don't understand variation. the scientist can identify what the relationship between Type A, B and C.
There is no way A comes from B or C.

bat->A-B&C is the evolution path, which can be identified on the RNA