Question: Was Mozart black?

No.

Both of his parents were from Salzburg in what is now Austria, Their families had been in region for decades and neither one of them was Black, Moorish nor Arabic according to the historical records. They appear to have been “White” people and they weren’t even “swarthy” like some Eastern and Southern Europeans were (and are even today).

Leopold Mozart

Anna Mozart

The idea that Mozart was black probably comes from a reference to Joseph Boulogne, Chevalier de Saint-George (December 25, 1745 – June 10, 1799.

Boulogne was known as “Le Mozart Noir” or “the black Mozart.” He was the first black man to lead France’s most important orchestras.

People who called Boulogne "the black Mozart" were making a comparison between the two musicians. They weren't saying that they were the same person.

Ideas often get twisted through repetition and misunderstanding. This appears to be one of those ideas.

http://www.orijinculture.com/community/le-mozart-noir-black-mozart-knowing-chevalier-de-saintgeorge/

The reason that "some people" think that Mozart was black is probably because those people are Americans.
Historically people were often referred to as "black" referring to hair colour (e.g. King Charles II) and whether you were a slave or not was more dependent on your religion than race (when black people started to become Christians then people started to become concerned about what was being done to them) & people were far less hung up on skin colour. The Romans would consider people darker than tem as "black" & lighter than them as "white" - & everybody not roman (or Greek) their inferiors.
In the USA, because of specific racist legislation - such as who was allowed to sit in a whites only train carriage or get married to - define blackness as "the one drop rule" - in the case in question was "one eighth." In places such as 18th century Europe - even 21st century Europe - nobody really cares. Someone of 1/8 black ancestry would not be considered black (& probably would not even KNOW they were black) except in the Deep South USA & that only due to having laws which would now be considered clinically insane about race. However these particular internal problems that Americans have with each other become projected onto the rest of the World (usually Africa) because of what is effectively cultural imperialism. If you google "black Mozart" images you will find the illustration of "The Black Mozart" is in fact Joseph Boulogne as is pointed out in the article by Katie Anne Holton.
If African Americans want to have musical black role models I myself would suggest Robert Johnson, Muddy Waters, Sonny Boy Williamson, Son House,
Lightnin Hopkins, Elmore James, JB Lenoir, RL Burnside, Leadbelly, Big Mama Thornton, Billie Holiday, Bessie Smith, Etta James... I could go on (you can probably discern my taste in music here).

Mozart was an amazingly original composer. It is particularly difficult to identify influences in the traditional sense because he virtually drank in everything he heard and no one source was formative of his music.

The wikipedia article on Mozart is particularly good.

http://en.wikipedia.org/wiki/Wolfgang_Amadeus_Mozart

The following extract focuses on the question of influences:

"Mozart always had a gift for absorbing and adapting valuable features of others' music. His travels helped in the forging of a unique compositional language.[76] In London as a child, he met J. C. Bach and heard his music. In Paris, Mannheim, and Vienna he met with other compositional influences, as well as the avant-garde capabilities of the Mannheim orchestra. In Italy he encountered the Italian overture and opera buffa, both of which deeply affected the evolution of his own practice. In London and Italy, the galant style was in the ascendent: simple, light music with a mania for cadencing; an emphasis on tonic, dominant, and subdominant to the exclusion of other harmonies; symmetrical phrases; and clearly articulated partitions in the overall form of movements.[77] Some of Mozart's early symphonies are Italian overtures, with three movements running into each other; many are homotonal (all three movements having the same key signature, with the slow middle movement being in the relative minor). Others mimic the works of J. C. Bach, and others show the simple rounded binary forms turned out by Viennese composers.

"As Mozart matured, he progressively incorporated more features adapted from the Baroque. For example, the Symphony No. 29 in A major K. 201 has a contrapuntal main theme in its first movement, and experimentation with irregular phrase lengths. Some of his quartets from 1773 have fugal finales, probably influenced by Haydn, who had included three such finales in his recently published Opus 20 set. The influence of the Sturm und Drang ("Storm and Stress") period in music, with its brief foreshadowing of the Romantic era, is evident in the music of both composers at that time. Mozart's Symphony No. 25 in G minor K. 183 is another excellent example.