The Kongo had a surprisingly big early empire (if a little fragmented), and overall they fought pretty well. But they left the tournament so quickly that their achievements are easily forgotten.
But hey, if you’re going to die early, die in a way that tells a story. The civs in the last four slides all outlived the Kongolese, but they didn’t have a GHOST FLEET to make them memorable. After a hard-fought but futile battle against the Boers, they kept flipping their cities until their melee units ran out, leaving a massive navy that was doomed never to see port again.