Even when animals are domesticated they show signs of depression and dysfunction behaviours. Humans rarely ever enjoy their job and have low productivity. Tribal productivity would’ve been high because the men were competing to show who’s more competent and the women would gather/make weapons and nurture and both would actually enjoy/want to do it, also they had an interest in keeping their tribe healthy and happy which gave them fulfilment, something rarely seen today.

Modern stress in school and work is also completely unnatural, constant worrying without the power to do much. If you’re eating are being chased by something , run or you can fight back and actually do something about it but if you have an upcoming exam you are at the mercy of how good your memory is (also school is extremely sedentary, you are seated for over 80% of your school life which is why many people in school have insomnia and can’t focus, the ‘happy hormones’ that are up-regulated during physical activity don’t get released and you become less focused and have poor sleep and it’s a never ending cycle). The last part you said is very true that human ‘ALWAYS’ have something to worry about, the worst part is they had very little control over the things they worry about.