Inventing the automobile has clearly made humanity less fit. Should we stop driving?
No. Going back to the stone age is not the solution. For the majority of our day, commuting without a vehicle will be impractical. So will coding without AI, especially as AI improves.
To retain human competency, we will have to find a novel solution. For walking, we created concentrated practice time - gyms/outdoor runs. Some evolution of leetcode, or even an AI guided training, might be the solution for coding skill preservation.