I'm 54 and doing a biology course. Never did it at exam level in school. I take exams next year. In the uk it was CSE or O and A level, now it is GCSE, which is CSE and O combined level and at 6th form college AS and A, which my son is doing in maths, chemistry and physics.
I'm doing the GCSE. I might do chemistry next. Hv and you have wetted my appetite to learn. I think i'll give physics a miss though, i'm not that clever lol.
You are never to old to learn! I also want to do a course on herbal medicine when i can fit it in.
Regarding the brain, they say use it or lose it, don't they.
You are right, everyone needs to know the basics at least. People selling stuff on the internet rely on our ignorance.