Well, in a short history of rm:
It started arround the en of the '80 (yes, msdos was arround and the rm too!) when ascii (the original company) started to make the brand rm programs)
Of course, imagine an rpg maker in the 80, they were first person crawlers like, you know, most rpgs at the time.
Thisd is when final fantasy wasn't or dragon quest wasn't put as a pilar of standards to make a jrpg game.
Then, we got to the era of super nintendo and they released rpg tkool super dante (Yes, they put dante as the name) and this is considered "the first rpg maker" probably because it was arguably the first with a tilemap editor and it was the first jrpg maker.
Then ascii continue making stuff, releasing the 95, the sim 98 and the 2k versions.
Later ascii fused with media works, wich became of course, ascii media works, now part of the set of corporations owned by kadokawa...
This is when enterbrain appears, enterbrain was a branch of kadokawa, focused on gaming, so it makes sense they were related to work with the next rm engines, well in part, they first just edited the 2k engine, making the popular 2k3, they continue making the rm engines untill vxa.
While yeah, now we have kadokawa directly saying "the maker is mine" and spike chunsoft (better know as the team who made mistery dungeon) behind the rtp assets probably, it's actually the same person behind the editor the whole time, after all kjadokawa is just moving him arround to different places, but yeah, this engine is mantained by a one man army (at least, part of it)
This side of the globe has a different, but funny history with RM:
Before degica wanted to distribute this engine to this side of the planet, one guy found the rm program, that guy was knowed as don migel, he brought the maker (not in a legal manner of course) to this side, he started with the 95 version, then the 2000, and 2k3 versions.
He spread this program he found like the plague, and because most of the guys over the internet were people who played SNES rpg games, and always loved those games, they said "woah, this program let's me make my chronno trigger secuel I always wanted", so people dig in.
Remember, people were doing it "for the love of rpgs" because they coudn't even sell their games, and while totally illegal, one has to admire people just wanting to use this engine.
You can find even more information about it anywere realle, even on wikipedia, so if you want to know the details you may check everywhere.
If you ask me, I pactually believe part of the reasons we have the rm engine today, was because don miguel promoted it (even if it was done illegaly) because degica actually saw an opportunity to bring this engine to this side of the globe with that (but that ideas are only mine, probably).