What are the main ideas of Marxism?

The way of life of a person, the society in which he lives, are determined by the existing economic system.
In the history of mankind, socio-economic formations have successively replaced one another, starting with the pre-class primitive communal system and ending with the capitalist system, and this formation is not yet the end of the road.
The replacement of one formation by another is always accompanied by an exacerbation of interclass contradictions and struggle.
Capitalism must inevitably be replaced by another, more progressive, humane, just formation, first socialism, then communism. When there will be no private property, wars, crime, forced labor and other shortcomings of the previous formations. A society of abundance and prosperity.