1. An offensive word meaning unpleasant, silly, incompetent, annoying, senile, elderly or childish person.
2. Surprisingly, it is also a personal pronoun in Old English 😁 (though spelled ġit)

This one's obvious to us all but I think it's fitting.

Why's it called Lemmy?

• Lead singer from Motörhead.
• The old school video game.
• The Koopa from Super Mario.
• The furry rodents.

Lemmings have a reputation for mindless groupthink, due to the unfortunate myth that lemmings are prone to jumping off cliffs. Lemmy is similarly misunderstood as a platform where strict ideological alignment is mandated and dissension is banned, but by and large the majority of moderation action on this instance is against spammers.

is there anything that has even more complicated name?

Also, why do FOSS people find recursive acronym so clever?

This one's easy. Lineage is ancestry, just like Lineage OS comes from CyanogenMod.