You move on, I'll comment ...

"there are people who collect that sort of African American memorabilia."

There are people who collect Nazi Memorabilia too.

The only collector of "piccaninny" or "coon" memorabilia that I am aware of is a museum
of Racist artefacts that exists to educate people on the difference between racist art and non racist art.

That kind of stuff is offensive, but in the old days society didn't give a much of a shit about the feelings of those they were offensive to.

The song is offensive because of its lyrics.

You could dress the singer up in a clown suit and throw pies at him, it wouldn't take the sting out of the words.

I'd bet a fortune that it wasn't composed by an African American.