18-month-old decides to stop eating his favorite foods and making a mess

This is probably a normal thing but as a new parent I wanted to ask My son is just about to turn 18 months but he started to not really eat any of the foods he used to like. Steak, chicken, fish, mac and cheese, oatmeal, etc. he really won't eat that stuff anymore including a lot of the fruits you used to love. Instead he likes to just throw it on the floor. I know it's probably normal for the throwing but how do we handle the eating? Seems like all he wants to do is eat snacky foods like puffs or crackers or things like that

On an unrelated question he started saying mama for like everything. Before he would actually like either not say anything or say words for something like Mama Dada baba things like that but now he says Mama for everything at all times like everything is mama mama mama this mama that and I'm wondering if this is normal