Did President Joe Biden tell Pope Francis that the latter was a "famous African-American baseball player?" Yes, he did. Biden was setting up a metaphor about age. After the comment, Biden proceeded to tell the pope about Leroy "Satchel" Paige, a Negro leagues and major league pitcher who played professionally well into middle age. Biden used a quote from Paige to say elderly persons like the two of them are only as old as they feel.
You're the famous African-American baseball player in America.
This is how the post looked on Instagram on November 2, 2021:
(Source: Instagram screenshot taken on Tue Nov 2 19:14:16 2021 UTC)
The clip in the Instagram post was stripped of that context. Biden, the nation's second Catholic president, visited the pope on October 29, 2021. Although footage of their entire conversation was not released, footage of Biden telling the story about Paige can be found starting at the 5:39-mark here. In it, Biden described how Paige, who was recruited to major league baseball at 42 years old, once responded to questions about his age with "How old would you be if you didn't know how old you were?" Biden, who is 78 years old, concluded the story by saying to the pope, who is 84 years old, "You're 65, I'm 60!"
A clip of the interaction is also embedded below:
(Source: YouTube video embedded on Tue Nov 2 19:16:57 2021 UTC)