I don’t disagree, there have been more than a few questionable decisions made by Disney execs on the MCU.
But…
I’m pretty sure Sam Wilson has been Captain America in the comics, more than once I think. I don’t think it’s a bad move for them to make this change, especially with how well they wrapped up Steve’s arc in Endgame. Actors age and using canon replacements is a great way to continue a franchise and introduce new stories.
Also: it’s not Black Falcon, it’s just Falcon. Gonna give you the benefit of the doubt that you weren’t being racist about it.