no idea how it has anything remotely to do with legos in the slightest
That is what Bionicle started out with. They were Lego
TECHNIC sets (
like these), as opposed to the Lego
SYSTEM sets that you seem to believe are the only Legos in existence. Each set had some kind of mechanical gimmick, the scorpion guy there could move the tail in a stinging manner, these mosquito things flapped their wings, there was a pair of crabs who were RC tanks, the Toa had gears that made their arms swing (or legs in one instance), and so on.
As time went on, though, Lego focused more on the canister sets than the boxes. For some strange reason, later canister sets eschewed the swinging arms/legs for gimmicky projectile launchers. This removed pretty much all the gears and mechanical features, thus severing every link to the Technic sets other than piece compatibility. Functionality gave way to form, and we were left with simple action figures. Even the later box sets were just bigger guys than the ones in the canisters who even with all their extra pieces had little more to offer.

Like this scowling idiot and his spider. They had no mechanical parts whatsoever. All you could do with it was open and close the spider's jaws and pose the limbs and head.
tl;dr Bionicle went from Technic with an action figure theme to just plain action figures. In its first few years it was very much related to Lego, but then deviated so much as to be something almost completely different.
Bioncles were part of the lowest and crappiest LEGO designs of the early 2000s.
That's not how you spell Jack Stone