Which character in Animal Farm represents the ideas of Karl Marx through their dream of animalism?

Old Major embodies the ideas of Karl Marx through his vision of animalism. He serves as the philosophical foundation for the revolution that the animals later undertake. In his speech to the other animals, Old Major articulates the principles of a society where animals can live free from human oppression and exploitation, echoing Marx's ideas of class struggle and the need for workers (or in this case, animals) to rise up against their oppressors (humans). His dream of a society where all animals share in the benefits of their labor is representative of the communist ideals articulated by Marx, making Old Major a pivotal character for understanding the ideological roots of the rebellion on the farm.

Characters like Boxer and Clover, while important to the story, represent the working class and their struggles rather than the foundational ideologies. Mr. Jones, as the human farmer, symbolizes the oppressive ruling class rather than the revolutionary ideas associated with Marx. Therefore, Old Major stands out as the key figure linking the narrative of "Animal Farm" to Marxist philosophy.