Tomato based sauces are VERY easy especially if you cheat and use Tinned tomatoes or passata.
Start by frying off a base of garlic, onion and maybe celery if you like.
Then add the tomatoes.
Then add other ingredients to flavour depending on the final dish so some examples:
Italian: oregano, basil, black pepper, parsley
Mexican: chilli, coriander, paprika, black pepper, cumin
Indian: turmeric, coriander, cumin, curry, cardamom
Chinese: ginger, cloves, 5 spice, star anise
Depending on your family's preferences.
Stir fry sauces are easy too. Again start with a base of onion and garlic then make up depending on preference or according to a recipe easily found online
I like satay best which is so easy (partly why I like it!) it's just peanut butter (yes really!) sweet chilli sauce, soy sauce, ginger and cumin
If you mean you can make a cheese sauce from scratch then you can make any other roux based sauce:
Parsley (ideal with fish), bechamel (lasagne) or just add your own flavours