I wrote a short baby leftist reading list a while back which might be useful!

1. Principles of communism (Engels). https://www.marxists.org/archive/marx/works/1847/11/prin-com.htm Explains the history of capitalism and what communism is in very basic terms.
2. Wage labour and capital (Marx). https://www.marxists.org/archive/marx/works/1847/wage-labour/ The very very basics marxist economic theory. Like a taster of Capital.
3. The three sources and three component parts of Marxism (Lenin). https://www.marxists.org/archive/lenin/works/1913/mar/x01.htm Super short essay by Lenin on the key concepts of marxism to tie everything together.
4. Imperialism (Lenin). https://www.marxists.org/archive/lenin/works/1916/imp-hsc/ We live in the world of imperialism, the highest stage of capitalism. Lenin in many ways predicted the 21st century evolution of capital.

Extra reads:

• Classic: Communist Manifesto (Marx+Engels). https://www.marxists.org/archive/marx/works/1848/communist-manifesto/ If you want to know what all the fuss is about.
• Feminism + Liberation: Women, Race & Class (Davis). Connects socialist feminist theory and black liberation theory. One of my favs of all time.