Chains can be used and abused for years and 1000s of miles before having any problems, and generally do not break due to simply being worn out. And I have never heard of a person so big or so strong they could break a good chain through sheer crank torque. Chains break because they are damaged - either by rough shifting under load or by a mangled tooth on the cogs. Or they break because they were not properly installed in the first place.
On new bikes, the shop where you buy the bike very rarely actually installs the chain - it is installed in the Taiwanese or chinese factory where the bike originated.
And the half-width chainring tooth is probably a 'shift gate' - a tooth with some material removed to allow the chain to pass up onto the next chainring.