ひとつまちがえば => Just (negligence) N3
Ability
ひとつ => A little N3
Repetition, habit
に気がつく => to notice; to realize N4
もうひとつ…ない => (not) anymore N2
Description
... ひとつ…ない => nothing/not at all… N2
Emphasize the negative meaning
…ひとつも…ない => cannot possibly be ~ N2
Evaluate
なにひとつ~ない => nothing/not at all… N3
Invariant
からつくる/でつくる => made from; made with N4
ひとつ…できない => cannot do the bigger things N3
Ability
ひとつには…ためである => Partly because of ... N3
Cause, reason
ひとり ... だけでなく => not only…, not just… N2
Add
てくれてありがとう => Thank you for doing A N4
Honorifics