How can Creationism be falsified?

[Loudmouth]

No good scientist says that. Or, more charitably, none that take their role of educating the public seriously.

"Given the size of vertebrate genomes (>1 × 10^9 bp) and the random nature of retroviral integration (22, 23), multiple integrations (and subsequent fixation) of ERV loci at precisely the same location are highly unlikely (24). Therefore, an ERV locus shared by two or more species is descended from a single integration event and is proof that the species share a common ancestor into whose germ line the original integration took place (14)."
Constructing primate phylogenies from ancient retrovirus sequences

That is a peer reviewed paper, and the authors aren't some chumps. One of the authors literally wrote the book on retroviruses.

How does one potentially falsify something that is proven?

The same way that we exonerate prisoners who were proven guilty beyond a reasonable doubt.

 

[The Barbarian]

on the same base that a truck is a car, or fossa is a cat:

If you think so, you've gotten confused between homology and analogy again.

Humans and chimps are about 9%+% similar genetically.

Fossas and Felids are genetically much more distant genetically.
fossa phylogeny - Google Search: