You're asking about historical roots and lineage, right?
Here goes for BJJ:
The original source of BJJ was Judo, specifically as it existed in the 1920s.
The commonly told story is that BJJ started when Carlos Gracie studied under Mitsuo Maeda (a Judoka and globetrotting prizefighter). Carlos then taught his brothers and the younger of those brothers, Helio Gracie, refined the art to make it more efficient and workable for smaller, weaker practitioners. From there the Gracies popularized their art via challenge matches and eventually the UFC.
This is at best an extreme simplification. There were other Judo instructors active in Brazil at the time. Carlos probably learned mostly from Donato Pires (a student of Maeda's) than directly from Maeda. There were other lineages of BJJ* besides the Gracie family, most notably that of Luiz França. The whole story about Helio single-handedly refining Judo into BJJ was a revisionist boast spread by Helio only after his brothers had passed away.
*(At the time, it wasn't called "Brazilian Jiu-jitsu", but simply "Jiu-jitsu". Apparently that was the term Maeda was using at the time, despite being a Kodokan black belt. Amusingly, later on when more Kodokan Judo practitioners started teaching in Brazil, Helio decried Judo as a watered-down fraud intended to deceive non-Japanese and declared that the Jiu-Jitsu taught by his own family was the original samurai Jiu-jitsu. This was before he made his claims of having single-handedly refined Judo into something new and better.)
At the start, there is no indication that Carlos or any of the other BJJ pioneers had any significant rank in Judo or direct connection back to the Kodokan. Carlos probably had no more than a couple of years training under Pires or Maeda and there is no evidence that he was awarded any rank at all. What these pioneers (notably Carlos Gracie, George Gracie, and Helio Gracie, but also Luiz França and Oswaldo Fadda) did was to fill in the gaps in their knowledge and experience with constant sparring practice, challenge matches, and picking the brains** of practitioners from related arts such as catch wrestling, lutra livre, Greco-Roman, Sambo, etc. This continued into the next generation (with the most accomplished BJJ fighter being Carlson Gracie Sr. ) and the next one after that (with the most accomplished fighters being first Rolls Gracie and then Rickson Gracie after Rolls' untimely death.) This hands-on experimental development resulted in an art which was closely related to Judo, but clearly distinct. Important differences included a much greater focus on newaza, a simplified approach to takedowns, fighting both with and without the gi, and a greater focus on using and dealing with strikes.
**(This brain-picking could take happen through friendly cross-training, study of fight opponents, or even reading books. Over the last couple of decades, study of video, both instructional and fight footage, has become another important avenue for the spread of knowledge.)
After the advent of the UFC and modern MMA, Brazilian Jiujitsu became popular worldwide. As the number of practitioners skyrocketed, most of the top instructors, fighters, and tournament competitors were no longer members of the Gracie family. (Although most could trace their lineage back to a Gracie family member within a couple of steps.) As the community of practitioners has become larger and larger, information has become more freely disseminated, and techniques continued to be tested in competition, there has been ongoing innovation within the art. This includes not just the invention of new techniques and tactics, but also ongoing refinement of fundamentals. A large part of the basics I learned 25 years ago are no longer considered "best practices" in terms of effectiveness.
It should be noted that not all of this evolution is universally accepted. A significant part of it is concerned with tactics within the modern ruleset of sport BJJ, which does not include striking and has a particular approach to scoring. Some old-school practitioners believe that this detracts from the real-world combative effectiveness of the art. However much of it is directly applicable to a more combative context. Improvements have been made to the mechanical efficiency of fundamental techniques, and tactics which are very applicable to a fight context (such as getting up rather than choosing to stay on the ground) are being emphasized more. Also, from an historical standpoint it should be noted that every generation of BJJ competitors, going back to Carlos and Helio Gracie, has participated in pure grappling events and not just in Vale Tudo/MMA fights.
As you should deduce from the above, there is no single founder of BJJ and no central organizing authority. Nor has the art ever had a static, standardized form. The closest I (or anyone else) could say that I come to the "original" form of the art is that I still practice it as primarily as a martial art for fighting and only secondarily as a combat sport for tournament competition. I can list my lineage back to the beginning of the art: Carlos Gracie -> Carlson Gracie Sr. -> Carlson Gracie Jr. -> Mike O'Donnell -> me. But that's just the chain of rank promotions. In reality, my knowledge of the art comes from all corners of the BJJ community, including people outside the Carlson Gracie lineage, peers, students, and practitioners of other arts such as Judo, wrestling, and Sambo.
