You can introduce peanut butter now if you like, she can have anything except honey and whole nuts (for the choking risk).
With regards to the salt, what she had yesterday was probably fine, but I'd start to look on packaging at the salt content. It's really quite easy to figure out how much they're getting from that (less than 1g is recommended).
I try to give only one meal a day and one snack with any salt in if possible, if I can't check for whatever reason, but I tend to look at her intake over a few days rather than one day iyswim?
For breakfasts I sometimes give weetabix which has a small amount of salt, but mostly porridge and fruit or yogurt and banana etc. Very occasionally she gets toast or a piece of homemade cake (no salt) with fruit and cheese.
For lunch I try to do things like homemade soup, vegetable frittata/ omlette, chunks of veg and fruit/ meat as they don't have salt in them and it means I can give a bit at dinner if I need to, or give toast/ croissant as an afternoon snack.
If we're having a salt free dinner eg, salmon with veg, baked potatoes, casserole (no salt stock cube), I can give baked beans on toast/ macaroni cheese etc for lunch.
God I've blabbed on a lot. I think a lot of salt is hidden in shop bought stuff like hummus so I'd avoid that if you can and make your own (it sounds scary but is super easy and takes 10 mins, ditto things like pesto) or give different toast toppings. DD likes tomato puree spread on hers, or covered in soup.
HTH a bit and hasn't sent you to sleep.