Can Someone Enlighten Me

Sooooo before I discovered this ratchet-ass website that I secretly love I only knew the terminologies " top, bottom, and switch". Then outta the buttcrack of dawn came new terms like "uke, seme, and seke"(lulz it's the fact that grammar check doesn't recognize "seke" as a word). Anyways, the new terms used to confuse me but I eventually learned them and now I'm just here wondering where they even came from. Were they always a thing and I was just living under a rock? 0_0