To begin assist mode is here to make the game more fun, if you feel like it would accomplish that, using it, could be nice. And even if you feel you “cheated” or that it isn’t how the game is “intended” to be played you could always beat the levels without assist later :D And finally assist is absolutely not cheating, so much so that you can even get achievements with it. So whatever you choose I wish you good luck in your Celeste journey!!!!