What are the key musical and historical features that distinguish 'the blues' from other musical genre?

The blues was forged under the conditions of slavery originally manifested in the form of work songs and spirituals by African Americans who were forced to transport such musics to the North American colonies. These work songs were particularly rhythmically distinctive as they often centred around chant-based ideas that fitted along to the tempos of their various work duties during the time of slavery, and their call and response nature would have helped sustain morale and a sense of community in a dark time. By the close of the 19th Century, such musics combined with European customs and instrumentation to form 'country blues', featuring a solo singer, often with a harmonica, and generally accompanied by a chordal instrument such as guitar and piano. Aided by new technologies and rapid urbanisation in the States, the blues continued on this trajectory of collaboration and change, forming new styles such as 'city blues' or 'urban blues' (thanks to such social changes), and would come to form a key part of Rock and Roll. Key musical features include:-4 beats in a bar (in 4/4 time)-Utilise the 12-bar blues form (I, IV, V- PLAYED ON THE PIANO IF NEEDED TO DEMONSTRATE)-4-bar phrases-3-line verse structure: second line repeats the first (often AAB). TRIVIA: this repetition of the first two lines often gave musicians time to improvise their final line!-Topics of love and loneliness, featuring slang-Concise instrumental solos featuring call and response-Employment of 'blue' notes- where the 3rd, 5th, and 7th degrees of the scale are flattened/bent by a semitone.