The reality is that you have thousands upon thousands of ancestors and millions of relatives. Too often, I am approached for help in finding one ancestor's parents. Also too often, I hear the same story about the years spent in researching that one person. I am also guilty of spending an inordinate amount of time researching one ancestral line and focusing on one ancestor. But during the past few years, I have learned that finding that elusive "brick wall" ancestor is often an unrealistic goal. Let me give an example of what I mean.
Let's call my ancestor "Mr. X." he was born in the late 1600s but we do not know where he was born. We also do not have either a birth or death date or even a marriage date. We have only the given name of his wife and we do not know where she was born either. We do know his name. On its face, we do not know enough to find this person even if records existed that might help us find him. By the way, he has a common name shared by multiple men living in the same community and during the same time period.
You might think this example extreme but this is essentially what I frequently hear from those seeking my help and in fact, they usually do not know the name of the elusive parent.
What else do I find when I begin to help these people? Almost always, there are family members who are known, such as children, for whom no research has been done. I saw one example about a week ago, where the parents were uncertain but the known end-of-line couple had about ten children listed and only two of them showed any sources supporting their identity in the family.
The is family history, not an individual biography effort. We search for families as units. If you move on to another generation back in any family line before you have researched every member of the family, you are building on sand and not even wet sand.
Here is what I suggest. Take a step back. Look at your research goals realistically. Start with an inventory of your known family lines. Make sure each generation is substantially supported by valid, believable sources from credible records. Make sure every family member is identified and substantiated. You might end up discovering that were never related to the elusive ancestor after all but even if you are related, you might find that it is more productive to focus on a different family line. You may even start to do some descendancy research.
I spent about 15 years or more looking for the birthplace of one great-great-grandfather and finally found the location only to further discover that there were no available records and if there are, I would have to travel to another country to try to find the records. Genealogy is not a competitive sport. We do not get ribbons or trophies for finding the elusive ancestor but we do have a better chance of finding him or her if we spend the time to fill in all the blanks before we tackle the difficult elusive ancestor.