No, it's not obvious.
There is no proof that the elder of Algetty is related to her. It can be anyone, even some irrelevant person.
The simple fact is that in the original timeline, Schala's pendant was lost.. The pendant itself may have only been found prior to 1000AD. It doens't mean that it was passed down in the family. As we know, Leene only had a coral hair pin. That should have been passed down, and there was no mention of a necklase anyway.
As for Ayla, over 65,000,000 years, the family tree would have enlargened by 100 fold. Crono and Marle are probably related when it goes back to Ayla. But then again, that applies to any other people of the Ioka tribe.
It's just implied that the Lubarians were the ones who touched the flame, and were enlightened, and that power was passed down in the Enlightened people.
But that would mean, as I said, that there was interbreeding, otherwise Crono and Marle would have nothing to unlock.
That is unless all Earthbound ones can do magic, but couldn't naturally have it unlocked.
If the Earthbound ones did not touch the flame, then they would not be as evolved, they'd be talking like Ayla. They don't, so that shows that even they had ancestors who touched the flame, but themselves did not naturally have it unlocked. Schala was probably born with the power already awaken, probably because the Zealian family is more purer in that power, if they were the original ones to touch the flame and such.