how do I beat Rainworld
Do not fear death
You know, I do actually want to elaborate on this. Rain World is a game where death is, as far as you are concerned, inconsequential. It doesn't mean anything except that you lose a karma level, which you can get back anyway. It gets hard sometimes but there's no money involved, it's not competitive. You're not even losing time when you die because it's just part of the time you spend playing the game.
When I say don't fear death, it's because fearing death in Rain World means that you avoid making decisions. If you always play to the safest options or panic when danger appears, you lose out on the opportunity to explore and learn what's possible. If you die, that's fine because unless there is a specific gate you're trying to get through and you need to preserve your karma, chances are you're not going to lose anything significant trying make that jump, apply that tech, fight that vulture, make that shot. You learn the game by interacting and interfacing with the worldspace and death is just another mechanic by which you do that.
Hunter's campaign is considered hard more for a reason. Beyond the more difficult enemy spawns and fact that dynamic difficulty is at maximum by default, your cycle timer counts down. They are the only slugcat that has to pay attention to their deaths, karma, and remaining cycles. Every other slugcat can take their time.
My point is that you can use that time to your advantage. Familiarize yourself with the cycle timer, maps, food spawns, enemy behaviors, how to use a grapple worm effectively. Move on when you're ready. More than anything, the most useful baseline skill for a Rain World player isn't killing lizards or pounce rolling; it's understanding your options and limits. Dying is a part of the learning experience. Learn what does and doesn't work so you're prepared for next time.
(For the record, the first time I beat the game, it was on Survivor. 45 deaths, and a large number of them were because I spent my first five hours playing the game ever just throwing myself at the outskirts lizards intentionally trying to figure out how to fight them without rocks.)