According to http://www.mainspringpress.com/AED-WILLIAMS.pdf,
Bert Williams recorded "In My Castle on The River Nile," Victor Monarch 991, in 1901.

But according to http://nfo.net/.CAL/tk5.html, the lyrics to "My Castle on the River Nile" were written by Ed Kirkeby who was "very active in the 1930s and 1940s, and very often worked with Thomas 'Fats' Waller's music."

Whatever the source, it seems the folk process has been at work on this song, as you can see by comparing the following versions. I think "baboon butler" makes more sense than "bamboo butler", and "inlaid diamonds on the floor" makes more sense than "lay your diamonds...".

Copied from http://www.mowglis.org/Songs/MyCastleOnTheRiverNile.html:

MY CASTLE ON THE RIVER NILE

Oh, in my castle on the river Nile
I'm going to live in elegant style:
Baboon butler at my door,
Diamond carpets all over the floor.

I'm goin' to marry the princess of Kalamazoo
My blood's going to change from red to blue:
Entertain royalty all the while
In my castle, castle, castle, on the river, river Nile!

Copied from http://www.geocities.com/yodatohi/mybody.htm

ON THE NILE

I'm gonna build my castle on the Nile
I will live in elegant style
Inlaid diamonds on the floor,
Bamboo butler at the door

I'm gonna marry my prince from Alaboo,
My blood will turn from red to blue
Imitating royalty all the while,
In my castle, castle, castle on the river Nile .

Bah bah bah bum bah bum bah bah bah bah bum,
Bum bah bum bah bah bah bah bah
Imitating royalty all the while,
In my castle, castle, castle on the river Nile,
The river Nile....

The following excerpt from the poem "Congo" by Vachel Lindsay, 1912, (Found at http://www.ipoet.com/archive/rhythmic/Lindsay/congo.html) contains some strikingly similar images:

A Negro fairyland swung into view,
A minstrel river where dreams come true.
The ebony palace soared on high
Through the blossoming trees to the evening sky.
The inlaid porches and casement shone
With gold and ivory and elephant-bone.
And the black crowd laughed till their sides were sore
At the baboon butler in the agate door,
And the well-known tunes of the parrot band
That trilled on the bushes of that magic land.