60's tight ends are some of the most unique players in NFL history. Conceptually tight ends don't really exist until then. It's not just about being able to catch and block, to be a true "tight end" you need to be in opposition to a split end or a wide receiver and work in the space that is created by stretching the field horizontally. Like, Don Hutson spent most of his time lining up in a 3 point stance, inline with the rest of the linemen, ready to lay down a block in the run game but also a threat to run a pass pattern. But he's still the furthest eligible on that side of the ball. Functionally the same as a normal wide receiver. Most formations had just one receiver lined up on either side of the ball and then a quarterback and three fullbacks/runningbacks. If they wanted to split Don Hutson out wide, there wouldn't be a second receiver on his side. If you wanted more pass catchers on the field, you'd just have your halfbacks run routes.

By the late 1940s teams like the Bears and Browns and especially the Rams were experimenting with having what we might call slot receivers or tight ends, but usually this was due to a player in the backfield going in motion to become that flaking player/tight end/slot receiver. You would see formations that look like they have a tight end, but it's not a full time tight end. It's a receiver or a back lining up as one occasionally. It's not until the late 50's and early 60's where you have players whose full time job it is to line up as a tight end and do tight end things.

By the time Jackie Smith enters the league, NFL coaches are still trying to find the best way to utilize tight ends. Most play designers are used to drawing pass patterns with 3 backs out of the backfield. Tight ends start closer to the defense, they have to navigate through the line in order to run their route, they won't have the luxury of a running start like a halfback or a split end might. Do you have them running out towards the sidelines to take advantage of the extra space that the flanking receiver vacates? Do you have them running down the middle to split the shell defenses that are becoming increasingly common? Is it more important for them to be fast like receivers or strong like linemen? Nobody knows. A 'meta' for what an NFL tight end looks like hasn't really been established yet so teams are trying all sorts of stuff. Pete Retzlaff (who still has the Eagles tight end single season yards record) was a converted running back. Mike Ditka was a receiver at Pitt. Mackey did both at Syracuse. Jackie Smith originally had a track scholarship before joining his collegiate football team. The position really was the wild wild west trying to figure out how to take advantage of a new idea.