“But our last name isn’t spelled that way!”
That is a phrase we often hear from people new to genealogy. They don’t realize that before the advent of social security in 1939, the spelling of names was a lot more flexible. How a name was spelled often depended upon who wrote it down, what they thought they heard and how they were accustomed to spelling that name. For example, one of my family names is DeWitt but I have seen it spelled Duett. If you sound both names out they sound an awful lot alike. McBryde is another example. During the span of my ancestor Elizabeth McBryde’s life, I have seen it spelled M’Bryde, MacBryde, MacBride and so on; same person, different scribes.
Another thing that can happen is the person can change how they spell their name for their own reasons. My Aunt Kathryn was born Catherine but liked the other spelling better and she began signing her name that way.
When you are looking for ancestors and are stumped, try sounding out the last name and think of different ways that the name could be spelled phonetically. Very often, you will find them under an alternate spelling.