Investors have capital, and want to see somebody produce something extra with that capital. The main variables are the size of the capital, and the risk profile the investor is prepared to accept.
Businesses require funding to grow[1]. The main variables are the nature of the reparations, and the control they are willing to concede.
The scale of the four dimensions above means that there is no one size fits method to transfer capital from investors to businesses and vice versa. For instance, Capital: $2 to $2bn; Risk: I'm prepared to lose it all, to I want guaranteed, fixed returns; Reparations: I'll pay 20% interest, to you can have non-negotiable dividend; Control: you can own debt, or you can have a seat on my board.
The evolutionary nature of the finance industry has gone from age old future contracts ("I'll give you $100 next October for your crop of wheat") to other more exotic derivatives e.g. Snowball Swap. Even if you as an individual do not need complex options like that, you may invest in a 401k that does.
[1]not limited to pure funding. Consider a manufacturer that makes a product that takes a year to make. If they sell to a foreign market, they cannot risk working and consuming raw materials for a year in one currency to be paid in another currency at the end of the order that varies. Thus, an FX Future gives the manufacturer the confidence to agree a deal and concentrate on the business fundamentals, not global currency markets.