Skip the soft sided cooler for starters...
As others have said; ask yourself what you expect to be doing and then what you might reasonably expect to need. Hard to have fun when you’re in pain, so learn prevention. Find a mindset that allows you to feel content wherever you are and it shouldn’t be too hard or require too much stuff... less is more but get real, right?
Ok...
daypack has first aid/ barebones survival kit, toiletries, water filter, raincoat, compass and thermometer, flashlight and batteries, and other things I can’t recall right off, truck always has key spares and tools and fluids. Also has sleeping bag and canvas tarp. Wallet, phone, money, less than bad karma. Then if I think I’m gunna go somewhere, I’ll add appropriate clothes and food and cooking gear. That’s anything from an old Svea 123 to a coleman426 stove coupled with a tea kettle, pot, and cast iron pan, a couple lanterns that use the same fuel- of course spares for those- then personal mess kit and water bottle. I used to use the Coleman steel belted, but switched to a rotomolded cooler last year... jury still out on that. Of course a fridge is nice but not needing one is better. If you can find eggs before they get washed you don’t have to cool them for a looooong time. Cheese is great and keeps for a couple days. Butter can be used for coffee instead of cream. camping is an excersize in ingenuity and conservatism coupled with creativity and resourcefulness
And if you're in Jackson grizzly repellent.
