I could be wrong, but if I remember right, Capcom retconned it to where they were Zombies, then they evolve into Crimson Heads, and then they evolve further into Lickers, which is their "Final form." So yeah, you're totally correct. IDK if that retcon is still in effect, or if Capcom has retconned their retcon (because let's face it, it's Capcom lol), but even if they have, it still makes sense as to why you see Lickers in RE2, but not in RE3. If anything you TECHNICALLY, continuity wise "In-universe" should see Crimson Heads in RE3 since that's what zombies turn into before they do lickers. But obviously they hadn't even been invented yet, because they didn't become part of canon until REmake. So if anything R3make should have Crimson Heads, but not Lickers. If that all made sense XD