The easier kind of contribution is to give to an existing organization. You can give money, time or expertise, but you are essentially playing the roll of a cog in the machine that they’ve already established.
The other kind of contribution is harder. It’s something you create that adds to humanity’s ability to survive and thrive. Einstein contributed an understanding of relativity. Ford contributed a working example of the assembly line.
We can’t all be Einstein or Ford, and your contribution doesn’t have to change the World. It just takes giving something of who you are rather than just what you have.