Capitalism is fundamentally based on private ownership. The rest falls out of it.
If I own and control something, and you own and control something else, trade is a natural byproduct.
If I own and control something, then of course I can reap benefits from it in the future. Building a completely isolated cabin in the woods that I have no intention of any other human even seeing is capitalist insofar as I assume property rights over it. I am investing time and effort now to build a large, durable structure that I may reap the interest for the remainder of my life, that interest being the durability in storms and the saved effort of rebuilding semi-permanent shelter on a recurring basis.
This is exactly profit brought in by one's assets and labors. I may choose to invest the saved time in other activities, such as tool-building to make the rest of my life easier.
Of course, no man is an island. The concept of capitalism means little in the absence of other humans, though as we see above it can still have some small meaning.
If I exist in some loose society where I interact with others and they may see and interact with my cabin, it matters much more if I assume property rights over it. Even if I do not ever allow another human to interact with the cabin, I reap the same benefits of my investment discussed above.
Note, I've not brought up the idea of money yet. Money is absolutely not required for us to be able to describe something as capitalistic. This is a common misunderstanding, as "capital" today often refers to cash and cash-valued assets.
Now, I am not trying to make a claim that capitalism is necessary for trade, simply that capitalism is sufficient for trade. Similarly capitalism is not necessary for the idea of investing for the long term, merely sufficient.
We could, of course, talk through a thought experiment where humans in a socialistic society build a cabin or cabins and this community accrues benefits as we've discussed.