It’s not literal guilt like in a criminal trial, it’s a collective responsibility.

“White guilt is a belief that white people bear a collective responsibility for the harm which has resulted from historical or current racist treatment of people belonging to other racial groups” (Wikipedia)

Here’s an analogy: if I see litter on the ground in my neighborhood, I’m not guilty of littering. But if I willfully ignore it and downplay it, rather than putting in extra effort to pick it up, my neighborhood will still have litter.

Race is an illusion we are all Homo Sapiens

On your litter analogy: I might be taking advantage of policies that have trash pickup on my street but don’t pickup trash on the other side of the tracks for “reasons”