well so far no one has rejected sea shanties,although they are comparitively recent compared to some.
A L LLOYD says The modern form of capitalism that gave rise to the great shipping lines,produced at the same time, the striking body of primitive folk songs that we call shanties.
john mearns[Scottish folklorist, singer broadcaster]remarked in an interview,that songs such as DRUMDELGIE , were not only sung in the bothys for recreation,but used as work songs by the farm labourers,different songs with different rhythms ,were used for ploughing or hand milking.
so logically we should also accept,songs sung in the american chaingang,scottish waiuking songs,and any songs that are used to assist manual labour[even if they are composed].