So do we count the AAFC which had multiple future NFL teams (just like the AFL). If so, the Browns have 4 more championships. Then you see teams like the Frankford Yellow Jackets and Providence Steam Rollers in the NFL.
I love the history of the game. I understand why they want a degree of uniformity and they accomplish that by using the word Championship vs Super Bowl. If the word is championship, nobody will dismiss what you're outlining. If the word is Super Bowl, we are talking about a specific title that didn't occur until the late 60's.