So, i want to speedrun this game, but can't do most, if any of the glitches. Could an entirely glitchless category be made, where no glitches at all are used?
Probably gonna be a no. There's All Levels and MAny%(all levels and bosses), but glitchless will likely never even be considered
Learn what you can and build your speedrun from there. Years ago, the game was straightforward and virtually glitchless. Over the years, a lot of work has been done to make the game faster. Start out small, then add on new strats as you can. You'll see your times improve. If you insist on speedrunning it glitchless, you won't be a better player of the game.
Regardless, speedrun what you want. It doesn't have to be reflected on the leaderboards 100% of the time.
There once was a 99 lives category but no one really cared and now it's gone. It would have been a pretty simple category for you to try and run. I would recommend just doing level runs until you get the hang of the entire game.
99 lives uses glitches though olo also it was never actually a category put on SRcom so it's not like it really went anywhere
Glitchless is a stupid idea: if you slidejump once, you setup a 'glitch' that is the longjump glitch, so this kind of category would be too boring. You can still go slow if you refuse to get good, and submit your run as any%/100%/All Levels.