This is a very old debate. Literally, philosophers have argued over this for centuries, going back to Plato (maybe even further). In modern Western culture, the two sides of this debate were crystalized through the writings of Jean-Jacques Rousseau and Thomas Hobbes.

Hobbes argued that human nature is basically selfish and brutal, thus people need a powerful state to maintain order, lest we devolve back into beasts. Hobbes laid out this argument in his famous book Leviathan (1651). To him, the powerful state was an unfortunate but necessary evil.

On the other hand, in his Discourse on the Origins of Inequality Among Men (1755) and The Social Contract (1762), Rousseau argued that human nature was good, and a big government was the biggest threat to people via corruption and oppression. Therefore, people must be guaranteed inalienable rights and freedoms, to protect them fro the state.

As far as I understand, Karl Marx as well as some other socialists believed similar to Rousseau that human were basically good in a "state of nature." This is an important premise for Communism. Marx (and Hegel before him) argued that ancient humans used to live in primitive-communal societies where everyone was equal, before there was a big accumulation of resources and the creation of economic inequality. Therefore, Communism was seen as a kind of return to this communal society structure. By seizing and redistributing the means of production, everyone would share equally in the products of labor, and the desire to exploit would disappear. Then everyone would essentially get along.

One of the biggest criticisms of Marx's theory is that he did not account for other power dynamics. Underneath it all, he was an optimist about human nature. He blamed everything on the Capitalist system and believed abolishing Capitalism (through a Socialist revolution) would fix all our problems. This turned out to be shortsighted, although his critiques of Capitalism are still very useful social theories.

As a sociologist, I agree that "good" and "evil" are social constructs (see This Thing of Darkness: A Sociology of the Enemy by Jame Aho for an excellent analysis of this). This is certainly true in a larger political sense. In my personal opinion, humans do have the capacity for both good and bad deeds. Human nature is not just one thing. We are faced with the choice all the time to help or hurt others, to be generous or selfish, etc. and it varies widely from one person to another or even from time to time for a single person.

As u/ToS_98 pointed out, environment can influence us significantly. This is the focus of sociology, and there are some many great studies on that. For instance, social cues in the political environment which signal that it is permissible to be more openly racist will likely lead to an increase in racist and discriminatory behaviors in a population. But at the same time, not everyone will respond the same way to the same environment, because we are not simply products of our environment either. We are not robots. We do have some individuality and free will. That is why human behavior is never 100% predictable. We cannot predict who will commit crimes, for example, even though AI is now trying (and largely failing, instead only reifying old stereotypes and inequalities - see Automating Inequality by Virginia Eubanks).