As in 1 Nephi 18:2, we have here variation between man and men. When Oliver Cowdery copied from 𝓞 to 𝓟 here in verse 25, he accidentally changed the singular man to the plural men. Although there is no other occurrence in the text of the precise phrase “use of man” (or “use of men”), there is one extensive passage in Ether that parallels 1 Nephi 18:25. Here the associated word is useful rather than use, but still the text has the singular man rather than the plural men:
This passage thus supports the singular “use of man” in the original manuscript for 1 Nephi 18:25.
Summary: Based on the original manuscript, restore the singular man in 1 Nephi 18:25 (“which were for the use of man”); usage in Ether 9:18–19 also supports the singular man in this context.