Fivethirtyeight says about 2/3 of gun deaths are suicides. Around 1/3 are homicides. A surprisingly small percentage (to me) are classified as accidents.[0]
Im not entirely surprised accidents are low, the places with the most guns have strong gun culture who have learned and put into practice gun safety from a young age. Many of the older folks have taken shooting classes or done shooting sport while in school, many of the younger generation have taken hunter safety courses, and of course military service people throughout the entire time, and all would teach basic gun safety. You will be kicked off any range for not being safe and most anyone who owns guns will very quickly correct anybody not being safe.
The amount of people who know nothing about guns and never shot one under proper supervision and then go out and purchase a firearm without researching anything are extremely low, so accidents remain pretty low.
Basic firearm safety instruction is part of it, and the other part is the general mechanical reliability of firearms. Modern firearms, as a general rule, will not fire themselves unless somebody or something interacts with them. Basic firearm safety instruction is often a short dogmatic set of rules[0] primarily focused on making sure people don't interact with the gun in a way that makes it likely to go off unintended. These two factors work together to keep people relatively safe from accidents around firearms most of the time.
There are some guns for which the basic dogmatic instruction is probably insufficient. Notably glocks; in some circles "glock" has become a verb, wherein to "glock yourself" means to accidentally shoot yourself in the leg with your glock while holstering or upholstering it. More specialized training can reduce the chances of this happening, but for this specific scenario and some others like it, the standard basic safety instructions fall a bit short in my opinion.
