steam (/water vapor)?
You do not know who made me, but I am made
Steam exists, but it's hard to define exactly what made it
You cannot see me, yet I am real
You can't usually see water vapor (though you can sometimes...), but it's definitely real
At one point I even surpassed Vegeta's power points
I don't know about this one
I sure have future too
Water vapor will eventually condense, and - through the water cycle - have infinite future "lives"
You can get me by doing a common job during the industrial revolution
Many jobs during the industrial revolution would have produced steam as a byproduct
You can also get me online, using specialty websites
"Steam" is an online distribution platform for video games etc.
Finally I have many lesser friends of my kind
Perhaps referring to the various forms of water (liquid, solid, etc.)? Unsure why these would be "lesser" though.