I had a period of time when money was very tight.
You can make a huge difference to your monthly finances by getting your weekly shopping down.
So I would opt for the cheapest unbranded version of cereal/beans/shampoo/whatever and trial it. If we liked it we kept buying it, if we didn't we went up a price point.
Base meals of what you have in the house already rather than what you fancy. Really use up every scrap. I hate waste for environmental reasons as much as financial, so veg lurking near the bottom of the fridge gets roasted and added to a tin of chickpeas or butter beans for a nutritious salad, or made into soup, or added to some sort of sauce to bulk it out. Lentils and oats also very good for bulking out meals.
Agree with PP that adults don't really need snacks if they're eating 3 proper meals. Kids can have cut up cucumber, carrot sticks, cheap mini apples from a multi-bag.
Porridge oats for breakfast. The cheapest fruit and veg is usually seasonal and/or doesn't have big air miles on it.
I have a breadmaker and make a loaf a couple of times a week which is cheap and filling, but only if you already have a breadmaker. I can make a loaf of bread by hand very easily too, but it took a bit of practice and does take more time. None of the nasty chemicals in packaged bread.
I genuinely enjoy eating this way. It keeps costs low, is rich in whole foods and low in UPF. So a win-win-win in my opinion.
Don't "go shopping" as a fun activity. Do it if you need something specific and use price comparison sites and vinted first.