And while you may have some substance behind your claim that the majority of population don't have enough brains (though this is debatable), the technology may be specifically intended to address this issue. In fact, even simple calculators do exactly that, though on a rather primitive level, of course
After all, any technology hinges on making human life better and easier in some way or other
Transhumanism? I havent considered that possibility
But you certainly should have
Though I wouldn't call that transhumanism or any other such scary word. In fact, we are moving in that direction all human history. Even a simple and rough stone axe can be considered as a tool augmenting human capabilities. Any working vaccine heavily tampers with human immune system (since otherwise it wouldn't work), so we are effectively already there (and for many years at that), whether you like it or not. In other words, it is a matter of degree, not of kind. Regarding experiences, what do you feel when you calculate some fancy numbers using a calculator? I don't think it would feel particularly different if you had a sort of "calculator" built directly into your brain (this is indeed an oversimplification of matters but it outlines the whole picture nevertheless). If anything, humans will remain the same humans in respect to their self-recognition and self-awareness