I don't think Van Gogh is a good example. There are certain artists whose work outlives them by centuries, not many, but we still talk about Michelangelo, da Vinci, Monet, etc. The rest of your post is accurate, though.
We simply haven't had enough time pass. Eventually, some day, people will forget who Julius Caesar was. It may take 50,000 years. It may take 500,000. They'll forget.
Counterpoint: an ancient Babylonian copper merchant is remembered to this day for being a no-good swindler due to complaints against him recorded in stone tablets [1]. Remembering things is only getting easier with better data storage. I guess you could just move the timeline out to the heat death of the universe, though.
The Mesopotamians were more preoccupied with writing down contracts in cuneiform than writing down historical fiction to last through the ages. Maybe because they were one of the first civilizations to thrive and to invent writing at all, they didn't know their oral traditions and history would be lost to the sands of time without writing them down.
We do have more insight into ancient Egyptian pharaohs and architects, however, as these details were more carefully preserved.
That being said, I'm sure 500K years from now, these details will all be buried on some thumb drive in an underground archive and our descendents will lack the drivers to decode them.
