This is with respect to the priority field in the modinfo.json that determines which mods overwrite which other mods.
priority [number] A number that determines the mod load order. 100 is default, lower numbers load first. Unless your mod depends on other or others depend on it, it is recommended to leave this at 100. https://forums.uberent.com/threads/guide-getting-your-mod-on-pamm.55189/
Does load first mean that conflicting files from subsequently loaded mods will be ignored or that other mods will replace files of previously loaded mods if they conflict with the most recently loaded mods?
I believe later shadowed files will overwrite previous ones. So the last loaded mod is guaranteed to be "intact".
