in case later complaint how different the WN and manga
the manga version is using LN as basic which have different approach, while the story is same
while WN is, you can say, a trial and error without editor version, which pure the author best thought in letter, it have a downside for me, it can be said as spoiler
in WN version, yes the first heroine, MC's osananajimi, is fall in love with the hero (literally this world hero, not MC), she is not faithful and choose hero instead MC, there's event after a few arc when the this osananajimi reject MC truthfully and say it just a child promise and ask him to move on, which he really move on, or run away
while in manga and LN the MC's osananajimi is faithful and refuse the kiss (incase the MC run away first so he don't see this) and search the MC together with his imouto
so basically, it's NTR in earlier chapter for WN
while i like netori, i don't enjoy NTR
and that's the first difference
ignoring that
it's the story of heartbroken MC who run away from home, got lost to the "mountain", get goddess blessing, eat many dangerous (anything) food, get stronger from that, and who know how, he get OP
the rest is just story about OP MC, easy fall in love which girl, get rejected, or so he think so, and run away again. the comedy is there, you laugh at the stupid MC
this translation is based on WN version, so if you don't enjoy it, the LN and manga maybe offer something different (which not translated yet for LN, and few chapter for manga)