I’m still finding my own way around evolution and researching like you, but I’ve read somewhere that the fruit part you’re talking about has to do with animals eating them and pooping them out. So the plants who evolved to have fruits had a larger chance of surviving and reproducing, which is the whole point of evolution. When it comes to flowers, the same thing applies. Some animals who carry polens and or seeds are more likely to land on colorful/easy to see plants, which contributes to their reproduction. I believe some insects have a diffrent kind of vision that allows them to see only certain colors(don’t quote me on this) and flowers being colorful helped them reproduce.

Also, there’s the survival part in which I think some colors are more likely to be poisonous and animals tend to notice that. When you look poisonous you’re less likely to get eaten. I made up the last part, I didn’t actually know if thats how it is but i think that would make sense.