Wolverine is the kind of success that few could have planned. He first appeared as a third wheel in a battle between Hulk and the Wendigo. At this period in Marvel history, debuting characters weren't the cream of the crop like in the Silver Age. Not every character was meant to be a blockbuster, and Wolverine definitely felt like someone who might never be seen again. Then Giant-Size X-Men #1 happened and Wolverine was a part of it. The rest is history.
Source：https://www.cbr.com/wolverine-origins-family-history-explanation/
