the idea that someone making mistakes or missing about a million braincells makes them "not MC material" is strange, considering how prolific the idiot hero is, and how many successful stories contain protagonists who make multiple, sometimes very very serious mistakes for any number of reasons, including a total lack of thought as to the appropriate treatment of thing thing they know nothing about.
story-impacting flaws are a foundation of character development and sorry to say, the omnipotent, seemingly infallible protagonists of the isekai genre are a more recent development (well...at least in japanese media) and far from what many would call a seal of quality.
it actually boggles my mind that a new adventure making a mistake at his own, completely harmless expense is somehow crossing the line.