How can I quickly locate the ancestor who is the furthest back in time on my family tree?
There really isn't any way. And if there was, you probably couldn't trust it. There is a lot of very questionable genealogy around so if some routine spit out a name, you would then have to go carefully back each generation verifying sources, which gets really hard when all of a sudden a third of the way back there are none. Be skeptical of any lines you do stumble on. A few years ago when fiddling around here in Family Tree seeing what kinds of lines I could follow back from my wife, I found a line that went back to Odin, not some semi-historical ancient norse king, but THE Odin. I wish I had recorded how I got there, but I didn't.1
You could use the Puzzilla partner website. Display your ancestor tree to, say, 10 generations, and then display the ancestor tree of any ancestor in that generation.
But, as @Gordon Collett explained, it is largely an exercise in fantasy.1
Many thanks to both of you; appreciated 😊0
a link about Puzzilla0
Install the free essential version of RootsMagic 8 on your computer. Then in RootsMagic open a new file and import from Family Tree. Use as starter PID your own PID. Set RootsMagic to import 99 generations of ancestors and 0 descendants. Turn off all the checkboxes; any extraneous data will slow down the tree import. Let it run. It could run for hours, so plan accordingly. Then use RootsMagic filters to find the earliest profiles.2