sharingan made him better.
The only comparsion we have is a narrow time before and after he got the sharingan.
Compare his skill before he got the sharingan to just after obito died.
U will find he got alot better in that comparion movement wise and jutsu wise because chadori needing u to spot ur blind spots quicker.
No point in fantasing what could have happened if didnt have the sharingan right now because kishi from since kahashi was small made him use the sharingan. It would be quite different if he got the sharingan later in his life like danzo for example. Then u have a decent comparion of what the ninja could achieve without the sharingan and with it .
The sole reason Kahashi is as smart as he is now with jutsu is because u got used to using an activted sharingan since he was young. So things like reading a fight to understanding how jutsu works is because of his skill with the sharingan.
U cant say without the sharingan kahashi would still be as sharp compared to how he became now with the sharingan.
U cant say anything else really.
The Master's Legacy
If a theory can't explain the mysteries of the past, it has little chance to explain the mysteries of the present and future.