There is more holes in this plot than swiss cheese.
Goblins only have 7 days life span, that's all. They are born with all the knowledge they need and more. They are also born with 1 skill that makes them a master in that field. They can transfer only the skill they are born with to another.
With this, the MC is able to make a tribe of savage goblins into a powerful country of cute goblins.
Everything the goblins do is done instantly. Traveling, crafting complex things, farming(i think, it doesn't show where most of the food comes from other than foraging some fruit), anything and everything is done instantly. It would have to be since they only live for 7 days.
The author always talk like a skill only lasts 14 days. 7 days with original, 7 with the gob that inherits it. But really it is 7 days with original, up to 7 days with inheritor. But that's only if a <day-old goblin is there...
The other biggest plot hole is passing position. Getting your successor up to speed and how his role is played out is also done instantly, no training required because that would detract from his 7 day life span.
clearly the 7 day old life span is NOT working for this story. The author is just forcing it
Honestly, any race with less than a 3 year life span can not make a basic level civilization. These 7 day defective goblins would at best be nomadic foragers like any animal out there.
To be more realistic the goblin should of had a minimum 5-6 years life span (ideally 11-14 years). This gives them enough time to complete a farming season, passing on roles that require first hand experience, permanent dwelling construction, building tools and other crafts of complex nature, etc... (though they still need to be born with language skill and other essential living skills like they already do)