i have no clue what mistake i made here. maybe someone understands?

this is just a wild guess but perhaps they didn't make the connection that the statue was of Rembrandt and that painter would then be a valid keyword?

I agree with Leaf. I can't think of anything else...

Put this in the title "Statue of Rembrandt"

and put something more in the description. several words at least.

Full name is: Rembrandt van Rijn.
Perhaps ad more details?
Most people know who Rembrandt was, but perhaps that is only because his name was not John...
When talking about 'a Vincent', nobody knows I mean a 'van Gogh' and nobody calls a Rubens a 'Peter Paul'.  

Colette, the problem is this is not Rembrandt van Rijn. This is a statue of him. Get it?
The subject of a picture is a statue, not a living man.

amsterdam...the statue may BE there, but you do not see amsterdam in the photo.

Just write "Rembrandt van Rijn statue" in the title.

Off course I saw it is a statue... It was not a suggestion for a title! 
I would suggest to add the word artist to the title too.
A painter can also be a painter of houses.
Perhaps: "Statue of the (famous) Dutch artist Rembrandt van Rijn"?