i can agree that most are confusing and that danzo being fire is absurd because he is wind, however most other ninjas are given them from a gameplay mechanic perspective as well as data book information, theres also a common theme that you can define a perosns element type based on there personal attributes and personality

in regards to this, this brings into question the actual viability of the healing tips ability, it might be incorrectly understanding, but a 40% increase in ninjutsu also increases healing by 40%, so if you are running a healing team with water ninjas, couldnt it possibly be better to run the water buff for the extra damage to try end it sooner instead of the healing only being a temporary buff? not really related to elemental status chocies themselves

now to me theres actually quite a few i would question outside of danzo who has all releases but predominately uses wind for combat because its his natural followed a bit further behidn by fire, i suppose to avoid clashes with onoki by having a wind fire barrier to fire lightnign for game mechanics... i get it but i dont really like it...

i dont know hinatas lightning premise but shes listed as fire and lightning in the data book, neji himself has 3 release types being earth fire and water i believe, i think both him and hinata have the largest affinity to fire though

now some others id question for example are tendo pain whos body yahiko has 0 affinity what so ever for lightning ninjutsus, he should really just be a water release ninja, because you dont magically change elements because somebdoy shoved some black rods in ya body

chiyo who id peg as a wind ninja especailly due to the wind symbols on all her scrolls and her placement as a sand ninja, the only major wind style using zone

i think shikamarus main release is supposed to be fire... but hes earth cause balacning i assume..

i definately question choji is the son of his father, both of which should be the same catergory, especially since choji has very little fire affinity

gai being fire release predominately but can ya say bout it..

this isnt going over everyone, but these are some examples of how the data book lists them

in regards to it, every user has a nature affinity and some can have ying and yang affinitys as well, and they existed before kakashi gave the paper explaination, i dont think he incldued them as the paper test can only help define elements, but the data books list there elemental order for the most part, and the ones i listed were the top affinitys, many have more then one, danzo himself having them all + ying and yang, you can find msot of these on the wiki pages to since hte databooks arent fully translated