For a game jam it's hard to make a really good tutorial, but usually "show don't tell" is a good way to get instructions across. Like you get have a roulette wheel image with an arrow going out on each color type, and then the arrow points to a short description. Ex. 0 would point to "Win acorns, deal damage", 1 would point to "Increase appetite", 2 would point to "dodge attack"
Then for explaining appetite say "bigger appetite = bigger multiplier"
For betting, maybe just say "bet on 0. higher bet = more acorns and damage, but higher cost. "
Upgrades made sense and were intuitive to me though.
Also build multiplier was kinda confusing at first so maybe say "bigger build multiplier = bigger multiplier" with the bigger appetite explanation.
Idk what i'm saying anymore lol, but show don't tell is really hard to execute sometimes, so even aiming for less text can make learning the game less daunting.
(Also im not a pro lol)