There is no other system today or in the past.
People have always traded, owned shares or goats or a humble house.
Centralised government is a relatively recent thing in terms of the human timeline.
I would argue this isn't actually true, though. Agriculture itself is a relatively recent thing in the human timeline, and centralized government developed simultaneously with it. Many argue that agriculture actually led to centralized government because it necessitated the concept of owning land, which requires some sort of centralized authority.
For a lot longer than that, nobody really owned the land and the economic systems were much more like socialism (in the economic sense, where the means of production is not owned privately) than capitalism.
The old rule was that if you lived on the land, it was yours, you owned it.
Today nobody in HK owns the land they live on or run their factories. Everything is leased from the government for 99 years. Are you really going to tell me that HK isnt capitalist ?
Of course not.
China also has some strange land is not owned but leased, are you really going to tell me they are communist because of the name and red flag ?
Of course not they are capitalist.
People are selfish, they do things for their own personal benefit and that my friend is definition of capitalism.