But we know that there are black holes and really don't know how they origin
There are numbers of different types of blackholes...how many types there are, I don’t really know, as I am neither an astronomer, nor an astrophysicist.
But the one I am familiar with Stellar Blackhole is that when a very massive star run out of hydrogen for thermonuclear fusion (or Stellar Nucleosynthesis, of which there are several types of SN), it either explode as in Supernova, or the gravity of star‘s very massive core, the star’s upper layers would collapse into the core, thereby creating blackhole. And anything that past the blackhole’s Event Horizon will get pull in and eventually become part of the dead star’s core.
So in Stellar Blackhole, the gravity collapse of star’s core is where blackhole originated.
As to Supermassive Blackholes within the centre of galaxies, you will have to ask someone with more knowledge than that I currently possess.
I can speculate that a galaxy’s supermassive blackhole (SMBH) might have originated from older generations of multiple massive stars, so probably multiple blackholes joined pulling each other to create increasingly larger blackhole, when the galaxy was younger.
The alternative origin for SMBH would be massive volume and very high density of molecular cloud of gases, could have cause gravity collapse, so instead of forming a star in such collapse, the collapse resulted in a supermassive blackhole.
As I said I am only speculating about the SMBH’s origins, so I’d need to read and research a bit more on the subject of SMBH.
